Communication system, terminal, and base station

ABSTRACT

There are provided a base station, a terminal, and a communication system in a wireless communication system in which a base station and a terminal communicate with each other, in which the base station and the terminal can efficiently perform communication. The communication system includes a higher layer processing unit 605 configured to configure, at the base station, for each terminal, a first reference signal configuration for configuring a measurement target for channel state reporting, configured to configure, at the base station, for each terminal, a second reference signal configuration specifying a resource element to be excluded from the target of data demodulation in a case where the terminal demodulates data, and configured to configure, at the base station, for each terminal, a third reference signal configuration for configuring a measurement target for which a reference signal received power is to be measured by the terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending application Ser. No.16/198,385, filed Nov. 21, 2018, which is a Continuation of applicationSer. No. 14/236,585, filed on Jan. 31, 2014, now U.S. Pat. No.10,142,949, issued Nov. 27, 2018, which is the National Phase of 35U.S.C. § 371 of International Application No. PCT/JP2012/069598, filedon Aug. 1, 2012, which claims the benefit under 35 U.S.C. § 119(a) toPatent Application No. 2011-169316, filed in Japan on Aug. 2, 2011, allof which are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a communication system, a terminal, anda base station.

BACKGROUND ART

In radio communication systems such as systems based on WCDMA (WidebandCode Division Multiple Access), LTE (Long Term Evolution), and LTE-A(LTE-Advanced), which are developed by 3GPP (Third GenerationPartnership Project), and Wireless LAN and WiMAX (WorldwideInteroperability for Microwave Access), which are developed by IEEE (TheInstitute of Electrical and Electronics engineers), a base station(cell, transmit station, transmitting device, eNodeB) and a terminal(mobile terminal, receive station, mobile station device, receivingdevice, UE (User Equipment)) each include a plurality oftransmit/receive antennas, and employ MIMO (Multi Input Multi Output)techniques to spatially multiplex data signals to realize high-speeddata communication.

In these radio communication systems, it is necessary for a base stationto perform various types of control on a terminal in order to realizedata communication between the base station and the terminal. To thisend, a base station notifies a terminal of control information usingcertain resources to perform data communication in the downlink anduplink. For example, a base station notifies a terminal of informationon resource allocation, information on the modulation and coding schemeof data signals, spatial multiplexing order information of data signals,transmit power control information, and so forth to realize datacommunication. Transmission of such control information may beimplemented using the method described in NPL 1.

Various methods may be used as communication methods based on MIMOtechniques in the downlink, examples of which include a multi-user MIMOscheme in which the same resources are allocated to different terminals,and a CoMP (Cooperative Multipoint, Coordinated Multipoint) scheme inwhich a plurality of base stations coordinate with each other to performdata communication.

FIG. 34 is a diagram illustrating an example of implementation of amulti-user MIMO scheme. In FIG. 34, a base station 3401 performs datacommunication with a terminal 3402 via a downlink 3404, and performsdata communication with a terminal 3403 via a downlink 3405. In thiscase, the terminal 3402 and the terminal 3403 perform multi-userMIMO-based data communication. The downlink 3404 and the downlink 3405use the same resources. The resources include resources in the frequencydomain and the time domain. Further, the base station 3401 performs beamcontrol for each of the downlink 3404 and the downlink 3405 using aprecoding technique or the like to mutually maintain orthogonality orreduce co-channel interference. Accordingly, the base station 3401 canrealize data communication with the terminal 3402 and the terminal 3403using the same resources.

FIG. 35 is a diagram illustrating an example of implementation of adownlink CoMP scheme. In FIG. 35, the establishment of a radiocommunication system having a heterogeneous network configuration usinga broad-coverage macro base station 3501 and an RRH (Remote Radio Head)3502 having a narrower coverage than the macro base station 3501 isillustrated. Consideration is now given to a configuration in which thecoverage of the macro base station 3501 includes part or all of thecoverage of the RRH 3502. In the example illustrated in FIG. 35, themacro base station 3501 and the RRH 3502 establish a heterogeneousnetwork configuration, and coordinate with each other to perform datacommunication with a terminal 3504 via a downlink 3505 and a downlink3506, respectively. The macro base station 3501 is connected to the RRH3502 via a line 3503, and can transmit and receive a control signal anda data signal to and from the RRH 3502. The line 3503 may be implementedusing a wired line such as a fiber optic line or a wireless line that isbased on relay technology. In this case, the macro base station 3501 andthe RRH 3502 use frequencies (resources) some or all of which areidentical, thereby improving the total spectral efficiency (transmissioncapacity) within the area of the coverage established by the macro basestation 3501.

The terminal 3504 can perform single-cell communication with the basestation 3501 or the RRH 3502 while located near the base station 3501 orthe RRH 3502. While located near the edge (cell edge) of the coverageestablished by the RRH 3502, the terminal 3504 needs to take measuresagainst co-channel interference from the macro base station 3501. Thereis under study a method for reducing or suppressing interference withthe terminal 3504 in the cell-edge area using a CoMP scheme asmulti-cell communication (coordinated communication) between the macrobase station 3501 and the RRH 3502. In the CoMP scheme, the macro basestation 3501 and the RRH 3502 coordinate with each other. The methoddescribed in NPL 2 is being studied as the CoMP scheme, by way ofexample.

FIG. 36 is a diagram illustrating an example of implementation of anuplink CoMP scheme. In FIG. 36, the establishment of a radiocommunication system having a heterogeneous network configuration usinga broad-coverage macro base station 3601 and an RRH (Remote Radio Head)3602 having a narrower coverage than that macro base station isillustrated. Consideration is now given to a configuration in which thecoverage of the macro base station 3601 includes part or all of thecoverage of the RRH 3602. In the example illustrated in FIG. 36, themacro base station 3601 and the RRH 3602 establish a heterogeneousnetwork configuration, and coordinate with each other to perform datacommunication with a terminal 3604 via an uplink 3605 and an uplink3606, respectively. The macro base station 3601 is connected to the RRH3602 via a line 3603, and can transmit and receive a reception signal, acontrol signal, and a data signal to and from the RRH 3602. The line3603 may be implemented using a wired line such as a fiber optic line ora wireless line that is based on relay technology. In this case, themacro base station 3601 and the RRH 3602 use frequencies (resources)some or all of which are identical, thereby improving the total spectralefficiency (transmission capacity) within the area of the coverageestablished by the macro base station 3601.

The terminal 3604 can perform single-cell communication with the basestation 3601 or the RRH 3602 while located near the base station 3601 orthe RRH 3602. In this case, while the terminal 3604 is located near thebase station 3601, the base station 3601 receives and demodulates asignal received via the uplink 3605. While the terminal 3604 is locatednear the RRH 3602, the RRH 3602 receives and demodulates a signalreceived via the uplink 3606. In addition, while the terminal 3604 islocated near the edge (cell edge) of the coverage established by the RRH3602 or near a midpoint between the base station 3601 and the RRH 3602,the macro base station 3601 receives a signal received via the uplink3605, and the RRH 3602 receives a signal received via the uplink 3606.Then, the macro base station 3601 and the RRH 3602 transmit and receivethese signals, which have been received from the terminal 3604, to andfrom each other via the line 3603, combine the signals received from theterminal 3604, and demodulate a composite signal. Through theseprocessing operations, improvements in the performance of datacommunication are expected. This is a method called Joint Reception,which enables improvements in the performance of data communication inthe cell-edge area or an area near a midpoint between the macro basestation 3601 and the RRH 3602 using a CoMP scheme in which the macrobase station 3601 and the RRH 3602 coordinate with each other for uplinkmulti-cell (multi-point) communication (coordinated communication).

CITATION LIST Non Patent Literature

-   NPL 1: 3rd Generation Partnership Project; Technical Specification    Group Radio Access Network; Evolved Universal Terrestrial Radio    Access (E-UTRA); Multiplexing and channel coding (Release 10), March    2011, 3GPP TS 36.212 V10.1.0 (March 2011).-   NPL 2: 3rd Generation Partnership Project; Technical Specification    Group Radio Access Network; Evolved Universal Terrestrial Radio    Access (E-UTRA); Further Advancements for E-UTRA Physical Layer    Aspects (Release 9), March 2010, 3GPP TR 36.814 V9.0.0 (March 2010).

SUMMARY OF INVENTION Technical Problem

In a radio communication system capable of coordinated communicationbased on a scheme such as a CoMP scheme, however, also in the downlink,a signal to be received by a terminal is appropriately transmitted froma base station, an RRH, or both the base station and the RRH, resultingin the throughput of the entire system being expected to increase.

The present invention has been made in view of the foregoing problems,and an object thereof is to provide a base station, a terminal, acommunication system, and a communication method that enable measurementof downlink received power and configuration of appropriate uplinktransmit power in a radio communication system in which a base stationand a terminal communicate with each other, so that the terminal canconfigure appropriate uplink transmit power.

Solution to Problem

(1) This invention has been made in order to overcome the problemdescribed above, and a communication system according to an aspect ofthe present invention is a communication system for performingcommunication between a base station and a terminal, including means forconfiguring, at the base station, for each terminal, a first referencesignal configuration for configuring a measurement target for channelstate reporting; means for configuring, at the base station, for eachterminal, a second reference signal configuration specifying a resourceelement to be excluded from the target of data demodulation in a casewhere the terminal demodulates data; means for configuring, at the basestation, for each terminal, a third reference signal configuration forconfiguring a measurement target for which a reference signal receivedpower is to be measured by the terminal; and means for receiving, at theterminal, information configured by the base station.

(2) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, in whichthe first reference signal configuration includes information relatingto a resource element on which measurement is performed, informationrelating to a subframe on which measurement is performed, andinformation relating to a power ratio of a downlink shared channel to areference signal.

(3) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, in whichthe second reference signal configuration includes information relatingto the resource element to be excluded, and information relating to asubframe in which the exclusion is to occur.

(4) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, in whichthe third reference signal configuration includes one or a plurality ofcombinations each including information relating to a resource elementon which measurement is performed, information relating to a subframe onwhich measurement is performed, and information relating to a powerratio of a downlink shared channel to a reference signal.

(5) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, in whichthe third reference signal configuration includes one or a plurality ofindexes each associated with an antenna port for a channel measurementreference signal.

(6) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, in whichat least some of resource elements to which a reference signaldesignated as a measurement target specified in the third referencesignal configuration is mapped are not included in resource elements towhich a reference signal designated as a measurement target specified inthe first reference signal configuration is mapped.

(7) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, whichfurther includes means for configuring an uplink transmit signal powerusing one path loss value determined on the basis of one or a pluralityof measurement targets specified by the base station among measurementtargets specified in the third reference signal configuration.

(8) Furthermore, a communication system according to an aspect of thepresent invention is the communication system described above, whichfurther includes means for reporting from the terminal to the basestation a received power calculated on the basis of the measurementtarget configured in the third reference signal configuration.

(9) Furthermore, a terminal according to an aspect of the presentinvention is a terminal for communicating with a base station, includingmeans for reporting a channel state to the base station on the basis ofa first reference signal configuration configured by the base station;means for determining a resource element to be excluded from the targetof data demodulation in a case where data is demodulated, on the basisof a second reference signal configuration configured by the basestation, to demodulate data; and means for measuring a reference signalreceived power on the basis of a third reference signal configurationconfigured by the base station.

(10) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, in which the first referencesignal configuration includes information relating to a resource elementon which measurement is performed, information relating to a subframe onwhich measurement is performed, and information relating to a powerratio of a downlink shared channel to a reference signal.

(11) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, in which the second referencesignal configuration includes information relating to the resourceelement to be excluded, and information relating to a subframe in whichthe exclusion is to occur.

(12) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, in which the third referencesignal configuration includes one or a plurality of combinations eachincluding information relating to a resource element on whichmeasurement is performed, information relating to a subframe on whichmeasurement is performed, and information relating to a power ratio of adownlink shared channel to a reference signal.

(13) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, in which the third referencesignal configuration includes one or a plurality of indexes eachassociated with an antenna port for a channel measurement referencesignal.

(14) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, in which at least some ofresource elements to which a reference signal designated as ameasurement target specified in the third reference signal configurationis mapped are not included in resource elements to which a referencesignal designated as a measurement target specified in the firstreference signal configuration is mapped.

(15) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, which further includes meansfor configuring an uplink transmit signal power using one path lossvalue determined on the basis of one or a plurality of measurementtargets specified by the base station among measurement targetsspecified in the third reference signal configuration.

(16) Furthermore, a terminal according to an aspect of the presentinvention is the terminal described above, which further includes meansfor reporting to the base station a received power calculated on thebasis of a measurement target specified in the third reference signalconfiguration.

(17) Furthermore, a base station according to an aspect of the presentinvention is a base station for communicating with a terminal, includingmeans for configuring a first reference signal configuration for eachterminal, and for receiving a channel state report on the basis of thefirst reference signal configuration; means for configuring a secondreference signal configuration for each terminal, and for specifying aresource element to be excluded from the target of data demodulation ina case where the terminal demodulates data, on the basis of the secondreference signal configuration; and means for configuring a thirdreference signal configuration for each terminal, and for giving aninstruction to measure a reference signal received power on the basis ofthe second reference signal configuration.

(18) Furthermore, a base station according to an aspect of the presentinvention is the base station described above, in which the firstreference signal configuration includes information relating to aresource element on which measurement is performed, information relatingto a subframe on which measurement is performed, and informationrelating to a power ratio of a downlink shared channel to a referencesignal.

(19) Furthermore, a base station according to an aspect of the presentinvention is the base station described above, in which the secondreference signal configuration includes information relating to theresource element to be excluded, and information relating to a subframein which the exclusion is to occur.

(20) Furthermore, a base station according to an aspect of the presentinvention is the base station described above, in which the thirdreference signal configuration includes one or a plurality ofcombinations each including information relating to a resource elementon which measurement is performed, information relating to a subframe onwhich measurement is performed, and information relating to a powerratio of a downlink shared channel to a reference signal.

(21) Furthermore, a base station according to an aspect of the presentinvention is the base station described above, in which the thirdreference signal configuration includes one or a plurality of indexeseach associated with an antenna port for a channel measurement referencesignal.

(22) Furthermore, a base station according to an aspect of the presentinvention is the base station described above, in which at least some ofresource elements to which a reference signal designated as ameasurement target specified in the third reference signal configurationis mapped are not included in resource elements to which a referencesignal designated as a measurement target specified in the firstreference signal configuration is mapped.

Accordingly, a base station can perform appropriate reference signalconfiguration for a terminal in accordance with use.

Advantageous Effects of Invention

According to this invention, in a radio communication system in which abase station and a terminal communicate with each other, the terminalcan measure downlink received power and configure appropriate uplinktransmit power.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a communication system forperforming data transmission according to a first embodiment of thepresent invention.

FIG. 2 is a diagram illustrating an example of one resource block pairused for mapping at a base station 101.

FIG. 3 is a diagram illustrating another example of one resource blockpair used for mapping at the base station 101.

FIG. 4 is a flowchart illustrating the details of an uplink signaltransmission process of a terminal according to the first embodiment ofthe present invention.

FIG. 5 is a schematic block diagram illustrating a configuration of thebase station 101 according to the first embodiment of the presentinvention.

FIG. 6 is a schematic block diagram illustrating a configuration of aterminal 102 according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of channels used for mappingat the base station 101.

FIG. 8 is a diagram illustrating the details of a channel-stateinformation reference signal configuration.

FIG. 9 is a diagram illustrating an example of the details of parametersrelated to a second measurement target configuration in step S403 inFIG. 4.

FIG. 10 is a diagram illustrating another example of the details of theparameters related to a second measurement target configuration in stepS403 in FIG. 4.

FIG. 11 is a diagram illustrating an example of the details of a CSI-RSmeasurement configuration.

FIG. 12 is a diagram illustrating another example of the details of aCSI-RS measurement configuration.

FIG. 13 is a diagram illustrating the details of a third measurementtarget configuration and report configuration in step S403 in FIG. 4.

FIG. 14 is a diagram illustrating an example of the details of a thirdmeasurement target configuration.

FIG. 15 is a diagram illustrating the details of the measurement objectEUTRA.

FIG. 16 is a diagram illustrating the details of a second measurementtarget configuration and report configuration in step S403 in FIG. 4.

FIG. 17 is a diagram illustrating the details of the second reportconfiguration.

FIG. 18 is a diagram illustrating an example of a report configuration.

FIG. 19 is a diagram illustrating the details of measurement reports.

FIG. 20 is a diagram illustrating the details of a EUTRA measurementresult list.

FIG. 21 is a diagram illustrating the details of a second measurementreport.

FIG. 22 is a diagram illustrating an example of the details of an uplinkpower control related parameter configuration.

FIG. 23 is a diagram illustrating another example of the details of anuplink power control related parameter configuration.

FIG. 24 is a diagram illustrating the details of a path loss referenceresource.

FIG. 25 is a diagram illustrating the details of path loss referenceresources based on the timing at which the terminal 102 has detected anuplink grant.

FIG. 26 is a diagram illustrating the details of path loss referenceresources based on a control channel region in which the terminal 102detects an uplink grant.

FIG. 27 is a diagram illustrating an example of a second uplink powercontrol related parameter configuration according to this embodiment ofthe claimed invention.

FIG. 28 is a diagram illustrating an example of a first uplink powercontrol related parameter configuration and a second uplink powercontrol related parameter configuration included in each radio resourceconfiguration.

FIG. 29 is a diagram illustrating an example of a second uplink powercontrol related cell-specific parameter configuration.

FIG. 30 is a diagram illustrating an example of a first uplink powercontrol related UE-specific parameter configuration and a second uplinkpower control related UE-specific parameter configuration.

FIG. 31 is a diagram illustrating an example of the path loss referenceresource.

FIG. 32 is a diagram illustrating another example of the path lossreference resource (other example 1).

FIG. 33 is a diagram illustrating another example of the path lossreference resource (other example 2).

FIG. 34 is a diagram illustrating an example of implementation of amulti-user MIMO scheme.

FIG. 35 is a diagram illustrating an example of implementation of adownlink CoMP scheme.

FIG. 36 is a diagram illustrating an example of implementation of anuplink CoMP scheme.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment of the present invention will be describedhereinafter. A communication system according to the first embodimentincludes a macro base station (base station, transmitting device, cell,transmission point, set of transmit antennas, set of transmit antennaports, set of receive antenna ports, component carrier, eNodeB), an RRH(Remote Radio Head, remote antenna, distributed antenna, base station,transmitting device, cell, transmission point, set of transmit antennas,set of transmit antenna ports, component carrier, eNodeB), and aterminal (terminal device, mobile terminal, reception point, receiverterminal, receiving device, third communication device, set of transmitantenna ports, set of receive antennas, set of receive antenna ports,UE).

FIG. 1 is a schematic diagram illustrating a communication system forperforming data transmission according to the first embodiment of thepresent invention. In FIG. 1, a base station (macro base station) 101transmits and receives control information and information data to andfrom a terminal 102 via a downlink 105 and an uplink 106 in order toperform data communication with the terminal 102. Similarly, an RRH 103transmits and receives control information and information data to andfrom the terminal 102 via a downlink 107 and an uplink 108 in order toperform data communication with the terminal 102. A line 104 may beimplemented using a wired line such as a fiber optic line or a wirelessline that is based on relay technology. In this case, the macro basestation 101 and the RRH 103 use frequencies (resources) some or all ofwhich are identical, thereby improving the total spectral efficiency(transmission capacity) within the area of the coverage established bythe macro base station 101. Such a network as established betweenneighboring stations (for example, between a macro base station and anRRH) using the same frequency is called a single frequency network(SFN). In FIG. 1, furthermore, the base station 101 notifies theterminal 102 of a cell ID, which is used for a cell-specific referencesignal (CRS) or a UE-specific reference signal (DL DMRS; DemodulationReference Signal, UE-RS; UE-specific Reference Signal) described below.The UE-specific reference signal is also referred to as the downlinkdemodulation reference signal (DL DMRS) or the terminal-specificreference signal. The RRH 103 may also notify the terminal 102 of a cellID. The cell ID notified by the RRH 103 may or may not be the same asthe cell ID notified by the base station 101. In the followingdescription, the base station 101 may represent the base station 101 andthe RRH 103 illustrated in FIG. 1. In the following description, theoperation between the base station 101 and the RRH 103 may represent theoperation between macro base stations or between RRHs.

FIG. 2 is a diagram illustrating an example of one resource block pairused for mapping at the base station 101 and/or the RRH 103 via thedownlink 105 or the downlink 107. FIG. 2 illustrates two resource blocks(resource block pair), each resource block being composed of 12subcarriers in the frequency domain and 7 OFDM symbols in the timedomain. Each subcarrier for a duration of one OFDM symbol is called aresource element (RE). Resource block pairs are arranged in thefrequency domain, and the number of resource block pairs may be set foreach base station. For example, the number of resource block pairs maybe set to 6 to 110. The width of the resource block pairs in thefrequency domain is called a system bandwidth. A resource block pair inthe time domain is called a subframe. In each subframe, sets of 7consecutive OFDM symbols in the time domain are each also called a slot.In the following description, resource block pairs are also referred tosimply as resource blocks (RBs).

Among the resource elements shown shaded, R0 to R1 representcell-specific reference signals (CRSs) for antenna ports 0 to 1,respectively. The cell-specific reference signals illustrated in FIG. 2are used in the case of two antenna ports, the number of which may bechanged. For example, a cell-specific reference signal for one antennaport or four antenna ports may be mapped. The cell-specific referencesignal can be configured for up to four antenna ports (antenna ports 0to 3). In other words, the cell-specific reference signal may betransmitted from at least any one of antenna ports 0 to 3.

The base station 101 and the RRH 103 may allocate the R0 to R1 todifferent resource elements, or may allocate the R0 to R1 to the sameresource element. For example, in a case where the base station 101 andthe RRH 103 allocate the R0 to R1 to different resource elements and/ordifferent signal sequences, the terminal 102 can individually calculatethe respective received powers (received signal powers) using thecell-specific reference signals. In particular, in a case where cell IDsnotified by the base station 101 and the RRH 103 are different, theconfiguration described above is made feasible. In another example, onlythe base station 101 may allocate the R0 to R1 to some of the resourceelements, and the RRH 103 may allocate the R0 to R1 to none of theresource elements. In this case, the terminal 102 can calculate thereceived power of the macro base station 101 from the cell-specificreference signals. In particular, in a case where a cell ID is notifiedonly by the base station 101, the configuration described above is madefeasible. In another example, in a case where the base station 101 andthe RRH 103 allocate the R0 to R1 to the same resource element and thesame sequence is transmitted from the base station 101 and the RRH 103,the terminal 102 can calculate combined received power using thecell-specific reference signals. In particular, in a case where the samecell ID is notified by the base station 101 and the RRH 103, theconfiguration described above is made feasible.

In the description of embodiments of the present invention, for example,the calculation of power includes the calculation of a power value, andthe computation of power includes the computation of a power value. Inaddition, the measurement of power includes the measurement of a powervalue, and the reporting of power includes the reporting of a powervalue. In this manner, the term “power” includes the meaning of a powervalue, as necessary.

Among the resource elements shown shaded, D1 to D2 represent UE-specificreference signals (DL DMRS, UE-RS) in CDM (Code Division Multiplexing)group 1 to CDM group 2. The UE-specific reference signals in CDM group 1and CDM group 2 are individually subjected to CDM using orthogonal codessuch as Walsh codes. In addition, the UE-specific reference signals inCDM group 1 and CDM group 2 are mutually subjected to FDM (FrequencyDivision Multiplexing). Here, the base station 101 can map UE-specificreference signals for up to rank 8 using eight antenna ports (antennaports 7 to 14), in accordance with the control signals and data signalsto be mapped to the resource block pair. The base station 101 may changethe spreading code length for CDM and the number of resource elements towhich a UE-specific reference signal is mapped, in accordance with theranks for which the UE-specific reference signals are mapped.

For example, the UE-specific reference signals for ranks 1 to 2 areformed using spreading codes with a length of 2 chips for antenna ports7 to 8, and are mapped to CDM group 1. The UE-specific reference signalsfor ranks 3 to 4 are formed using spreading codes with a length of 2chips for antenna ports 9 to 10 in addition to antenna ports 7 to 8, andare mapped to CDM group 2. The UE-specific reference signals for ranks 5to 8 are formed using spreading codes with a length of 4 chips forantenna ports 7 to 14, and are mapped to CDM group 1 and CDM group 2.

In the UE-specific reference signals, a scrambling code is furthersuperimposed on an orthogonal code for each antenna port. The scramblingcode is generated based on a cell ID and a scrambling ID, which arenotified by the base station 101. The scrambling code is generated basedon, for example, a pseudo-noise sequence generated based on a cell IDand a scrambling ID, which are notified by the base station 101. Forexample, the scrambling ID has the value 0 or 1. Furthermore, ascrambling ID and information indicating the antenna port to be used maybe jointly coded, and information indicating them may be indexed.

Among the resource elements shown shaded in FIG. 2, the area composed ofthe first three OFDM symbols is configured as an area in which a firstcontrol channel (PDCCH; Physical Downlink Control Channel) is arranged.The base station 101 may set, for each subframe, the number of OFDMsymbols in an area in which the first control channel is arranged. Thearea including the resource elements in a solid white color representsan area in which a second control channel (X-PDCCH) or a shared channel(PDSCH; Physical Downlink Shared Channel) (physical data channel) isarranged. The base station 101 may set, for each resource block pair, anarea in which the second control channel or the shared channel isarranged. The ranks for the control signals to be mapped to the secondcontrol channel or the data signals to be mapped to the shared channelmay be set to be different from the ranks for the control signals to bemapped to the first control channel.

Here, the number of resource blocks may be changed in accordance withthe frequency bandwidth (system bandwidth) that the communication systemuses. For example, the base station 101 can use 6 to 110 resource blocksin the system band, the unit of which is also called a component carrier(CC; Component Carrier, Carrier Component). The base station 101 canalso configure a plurality of component carriers for the terminal 102through frequency aggregation (carrier aggregation). For example, thebase station 101 can configure five component carriers contiguous and/ornon-contiguous in the frequency domain for the terminal 102, eachcomponent carrier having a bandwidth of 20 MHz, thereby totaling abandwidth of 100 MHz, which can be supported by the communicationsystem.

Here, the control information is subjected to processing such asmodulation processing and error correction coding processing using acertain modulation scheme and coding scheme to generate a controlsignal. The control signal is transmitted and received on the firstcontrol channel (first physical control channel) or the second controlchannel (second physical control channel) different from the firstcontrol channel. The term physical control channel, as used herein, is atype of physical channel and refers to a control channel defined in aphysical frame.

In one aspect, the first control channel is a physical control channelthat uses the same transmit port (antenna port) as that used for thecell-specific reference signal. The second control channel is a physicalcontrol channel that uses the same transmit port as that used for theUE-specific reference signal. The terminal 102 demodulates a controlsignal to be mapped to the first control channel using the cell-specificreference signal, and demodulates a control signal to be mapped to thesecond control channel using the UE-specific reference signal. Thecell-specific reference signal is a reference signal common to all theterminals 102 within a cell, and is a reference signal available to anyof the terminals 102 since it is included in all the resource blocks inthe system band. Accordingly, the first control channel can bedemodulated by any terminal 102. In contrast, the UE-specific referencesignal is a reference signal included in only allocated resource blocks,and can be adaptively subjected to beamforming processing in the samemanner as that for the data signal. Accordingly, adaptive beamforminggain can be obtained on the second control channel.

In a different aspect, the first control channel is a physical controlchannel over OFDM symbols located in a front part of a physicalsubframe, and may be arranged in the entire system bandwidth (componentcarrier (CC)) over these OFDM symbols. The second control channel is aphysical control channel over OFDM symbols located after the firstcontrol channel in the physical subframe, and may be arranged in part ofthe system bandwidth over these OFDM symbols. Since the first controlchannel is arranged on OFDM symbols dedicated to a control channellocated in a front part of a physical subframe, the first controlchannel can be received and demodulated before OFDM symbols located in arear part of the physical subframe, which are used for a physical datachannel. The first control channel can also be received by a terminal102 that monitors only OFDM symbols dedicated to a control channel. Inaddition, since the resources used for the first control channel can bescattered and arranged in the entire CC, inter-cell interference for thefirst control channel can be randomized. In contrast, the second controlchannel is arranged on OFDM symbols in a rear part, which are used for ashared channel (physical data channel) that a terminal 102 undercommunication normally receives. The base station 101 can performfrequency division multiplexing on the second control channel toorthogonally multiplex (multiplex without interference) second controlchannels or the second control channel and the physical data channel.

In a different aspect, furthermore, the first control channel is acell-specific physical control channel, and is a physical channel thatboth a terminal 102 in the idle state and a terminal 102 in theconnected state can acquire. The second control channel is a dedicatedphysical control channel, and is a physical channel that only a terminal102 in the connected state can acquire. The term idle state, as usedherein, refers to a state (RRC_IDLE state) where data is not immediatelytransmitted or received, such as a state where no RRC (Radio ResourceControl) information is accumulated in the base station 101. The termconnected state, in contrast, refers to a state where data can beimmediately transmitted or received, such as a state (RRC_CONNECTEDstate) where network information is held in the terminal 102. The firstcontrol channel is a channel that the terminal 102 can receive withoutdepending on dedicated RRC signaling. The second control channel is achannel configured with dedicated RRC signaling, and is a channel thatthe terminal 102 can receive through dedicated RRC signaling. That is,the first control channel is a channel that any terminal can receiveusing a pre-limited configuration, and the second control channel is achannel with easily modified dedicated configuration.

FIG. 3 is a diagram illustrating a resource block pair to whichchannel-state information reference signals (CSI-RS) for eight antennaports have been mapped. FIG. 3 depicts the mapping of channel-stateinformation reference signals when the number of antenna ports (thenumber of CSI ports) of a base station is 8. FIG. 3 also depicts tworesource blocks within one subframe.

Among the resource elements in a solid color or shaded with obliquelines in FIG. 3, the UE-specific reference signals of CDM group numbers1 to 2 (reference signals for data signal demodulation) are representedby D1 to D2, respectively, and the channel-state information referencesignals of CDM group numbers 1 to 4 are represented by C1 to C4,respectively. In addition, data signals or control signals are mapped toresource elements other than the resource elements to which thesereference signals have been mapped.

In the respective CDM groups, the channel-state information referencesignals are implemented using 2-chip orthogonal codes (Walsh codes), andeach orthogonal code is allocated a CSI port (channel-state informationreference signal port (antenna port, resource grid)). Code divisionmultiplexing (CDM) is performed every two CSI ports. In addition, therespective CDM groups are frequency-division multiplexed. The8-antenna-port channel-state information reference signals for CSI ports1 to 8 (antenna ports 15 to 22) are mapped using four CDM groups. Forexample, in the CDM group C1 of the channel-state information referencesignals, the channel-state information reference signals for CSI ports 1and 2 (antenna ports 15 and 16) are subjected to CDM, and are mapped. Inthe CDM group C2 of the channel-state information reference signals, thechannel-state information reference signals for CSI ports 3 and 4(antenna ports 17 and 18) are subjected to CDM, and are mapped. In theCDM group C3 of the channel-state information reference signals, thechannel-state information reference signals for CSI ports 5 and 6(antenna ports 19 and 20) are subjected to CDM, and are mapped. In theCDM group C4 of the channel-state information reference signals, thechannel-state information reference signals for CSI ports 7 and 8(antenna ports 21 and 22) are subjected to CDM, and are mapped.

If the number of antenna ports of the base station 101 is 8, the basestation 101 can configure up to eight layers (ranks, spatialmultiplexing layers, DMRS ports) of data signals or control signals, andcan configure, for example, two data signal layers and one controlsignal layer. In the respective CDM groups, the UE-specific referencesignals (DL DMRS, UE-RS) are implemented using 2-chip or 4-chiporthogonal codes in accordance with the number of layers, and aresubjected to CDM every 2 layers or 4 layers. In addition, each CDM groupof the UE-specific reference signals is frequency-division multiplexed.The 8-layer UE-specific reference signals for DMRS ports 1 to 8 (antennaports 7 to 14) are mapped using two CDM groups.

The base station 101 can transmit the channel-state informationreference signal in a case where the number of antenna ports is 1, 2, or4. The base station 101 can transmit the channel-state informationreference signal for one antenna port or two antenna ports using the CDMgroup C1 of the channel-state information reference signals illustratedin FIG. 3. The base station 101 can transmit the channel-stateinformation reference signal for four antenna ports using the CDM groupsC1 and C2 of the channel-state information reference signals illustratedin FIG. 3.

The base station 101 and the RRH 103 may allocate a different resourceelement to each of the C1 to C4, or may allocate the same resourceelement to each of the C1 to C4. For example, in a case where the basestation 101 and the RRH 103 allocate a different resource element and/ordifferent signal sequence to each of the C1 to C4, the terminal 102 canindividually calculate the respective received powers (received signalpowers) and the respective channel states of the base station 101 andthe RRH 103 using the channel-state information reference signals. Inanother example, in a case where the base station 101 and the RRH 103allocate the same resource element to each of the C1 to C4 and the samesequence is transmitted from the base station 101 and the RRH 103, theterminal 102 can calculate combined received power using thechannel-state information reference signals.

A flowchart in FIG. 4 illustrates how the terminal 102 measuresreference signals (cell-specific reference signal, channel-stateinformation reference signal), reports a received power to the basestation 101, computes a path loss on the basis of the measurementresults, computes the uplink transmit power on the basis of the computedpath loss, and transmits an uplink signal at the computed uplinktransmit power. In step S403, the base station 101 performs parameterconfiguration for the terminal 102 concerning measurement and reportingof the reference signals. Parameters related to a second measurementtarget configuration, a second report configuration, a third measurementtarget configuration, and a third report configuration can be configuredin step S403. Although not illustrated here, a first measurement targetconfiguration is pre-configured in the terminal 102. The measurementtarget of the first measurement target configuration (first measurementtarget) may always be the cell-specific reference signal for antennaport 0 or the cell-specific reference signals for antenna ports 0 and 1.

That is, there is a possibility that the first measurement targetconfiguration may target a pre-designated specific reference signal andantenna port. In contrast, the second measurement target configurationconfigured by the base station 101 targets the channel-state informationreference signal, and a resource (antenna port) that is a measurementtarget of the second measurement target configuration may beconfigurable.

The second measurement target may include one resource or a plurality ofresources. The details of these parameters will be described below. Thethird measurement target configuration configured by the base station101 may include a configuration for measuring a reference signaltransmitted from an unconnected cell, as described below. For example, areference signal that is a measurement target of the third measurementtarget configuration (third measurement target) may always be thecell-specific reference signal transmitted from antenna port 0 or thecell-specific reference signals transmitted from antenna ports 0 and 1.That is, there is a possibility that the third measurement targetconfiguration may target a pre-designated specific reference signal anda reference signal transmitted from a specific antenna port in anunconnected cell. The term unconnected cell, as used herein, can mean acell with no parameters configured via RRC.

In another aspect, a cell-specific reference signal transmitted from anunconnected cell may be generated using a physical ID (physical cell ID)different from that of a cell-specific reference signal transmitted fromthe connected cell. Here, the base station 101 notifies the terminal 102of a physical ID (physical cell ID), a carrier frequency (centerfrequency), and so forth using the third measurement targetconfiguration, allowing the terminal 102 to measure the received signalpower of a cell-specific reference signal transmitted from anunconnected cell (a cell with no RRC parameters configured) (see FIG.15). Each of the second report configuration and the third reportconfiguration includes a configuration related to the timing at whichthe terminal 102 transmits measurement results in a measurement report,such as an event used as a trigger.

Subsequent description will be made of step S405. In step S405, in acase where the first measurement target configuration described abovehas been performed, the terminal 102 measures the reference signalreceived power of the first measurement target configured in the firstmeasurement target configuration. In a case where the second measurementtarget configuration described above has been performed, the terminal102 measures the reference signal received power of the secondmeasurement target configured in the second measurement targetconfiguration. In a case where the third measurement targetconfiguration has been performed, the terminal 102 measures thereference signal received power of the third measurement targetconfigured in the third measurement target configuration. Subsequentdescription will be made of step S407. Parameters related to a firstmeasurement report and/or a second measurement report can be configuredin step S407.

The first measurement report may relate to the received signal power ofthe measurement target configured in the first measurement targetconfiguration and/or the third measurement target configurationdescribed above. In contrast, the second measurement report may relateto the received signal power of the measurement target configured in thesecond measurement target configuration described above. In addition,the second measurement report described above is associated with some ofone or more measurement results of the reference signal received power(RSRP) of the second measurement target configured in the secondmeasurement target configuration. There is a possibility that the secondmeasurement report described above may configure which resource in thesecond measurement target is to be reported in the measurement result.Which resource is to be reported in the measurement result may benotified by indexes relating to CSI ports 1 to 8 (antenna ports 15 to22), or may be notified by indexes relating to frequency-time resources.Accordingly, in step S407, in a case where the first measurement reportdescribed above has been configured, the measurement result of thereference signal received power of the first measurement target and/orthe third measurement target configured in the first measurement targetconfiguration and/or the third measurement target configuration isreported. In a case where the second measurement report described abovehas been configured, at least one of one or more measurement results ofthe reference signal received power of the second measurement targetconfigured in the second measurement target configuration is reported.As described above, there is a possibility that the second measurementreport may configure of which resource in the second measurement targetthe measurement result is to be reported.

Subsequent description will be made of step S408. In step S408,parameters related to uplink power control (UplinkPowerControl, TPCCommands, etc.) can be configured. The parameters may include aparameter configuration indicating which of the first path loss based onthe received signal power measured and reported using the firstmeasurement target configuration and first measurement report describedabove and the second path loss based on the received signal powermeasured and reported using the second measurement target configurationand second measurement report described above is to be used as a pathloss to be used for the computation of the uplink transmit power. Thedetails of these parameters will be described below.

Subsequent description will be made of step S409. In step S409, theuplink transmit power is computed. The computation of the uplinktransmit power is performed using a downlink path loss between the basestation 101 (or the RRH 103) and the terminal 102. The downlink pathloss is calculated from the received signal power of the cell-specificreference signal, that is, the measurement results of the firstmeasurement target, or the received signal power of the channel-stateinformation reference signals, that is, the measurement results of thesecond measurement target, which is measured in step S405. Since thereference signal transmit power is also required for the calculation ofa path loss, the second measurement target configuration described abovemay include information concerning the reference signal transmit power.Accordingly, the terminal 102 holds the first path loss determined onthe basis of the reference signal received power of the firstmeasurement target configured in the first measurement targetconfiguration and the second path loss determined on the basis of thereference signal received power of the second measurement targetconfigured in the second measurement target configuration. The terminal102 computes the uplink transmit power using one of the first path lossand second path loss in accordance with the uplink power control relatedparameter configuration configured in step S403. Subsequent descriptionwill be made of step S411. In step S411, an uplink signal is transmittedat the transmit power value determined in step S409.

FIG. 5 is a schematic block diagram illustrating a configuration of thebase station 101 of the present invention. As illustrated in FIG. 5, thebase station 101 includes a higher layer processing unit 501, a controlunit 503, a receiving unit 505, a transmitting unit 507, a channelmeasurement unit 509, and a transmit/receive antenna 511. The higherlayer processing unit 501 includes a radio resource control unit 5011,an SRS configuration unit 5013, and a transmit power configuration unit5015. The receiving unit 505 includes a decoding unit 5051, ademodulation unit 5053, a demultiplexing unit 5055, and a radioreceiving unit 5057. The transmitting unit 507 includes a coding unit5071, a modulation unit 5073, a multiplexing unit 5075, a radiotransmitting unit 5077, and a downlink reference signal generation unit5079.

The higher layer processing unit 501 performs processing of the packetdata convergence protocol (PDCP) layer, the radio link control (RLC)layer, and the radio resource control (RRC) layer.

The radio resource control unit 5011 included in the higher layerprocessing unit 501 generates information to be mapped to each channelin the downlink or acquires it from the higher node, and outputs it tothe transmitting unit 507. The radio resource control unit 5011 furtherallocates a radio resource on which the terminal 102 is to arrange aphysical uplink shared channel PUSCH (Physical Uplink Shared Channel),which is data information in the uplink, from among the uplink radioresources. The radio resource control unit 5011 also determines a radioresource on which a physical downlink shared channel PDSCH (PhysicalDownlink Shared Channel), which is data information in the downlink, isto be arranged from among the downlink radio resources. The radioresource control unit 5011 generates downlink control informationindicating the allocation of the radio resources, and transmits thedownlink control information to the terminal 102 through thetransmitting unit. When allocating a radio resource on which a PUSCH isto be arranged, the radio resource control unit 5011 preferentiallyallocates a radio resource with high channel quality on the basis of theuplink channel measurement results input from the channel measurementunit 509.

The higher layer processing unit 501 generates control information tocontrol the receiving unit 505 and the transmitting unit 507 on thebasis of uplink control information (ACK/NACK, channel qualityinformation, scheduling request) notified by the terminal 102 on thephysical uplink control channel PUCCH and the buffer state notified bythe terminal 102 or various types of configuration information on eachterminal 102 which are configured by the radio resource control unit5011, and outputs the control information to the control unit 503.

The SRS configuration unit 5013 configures a sounding subframe, which isa subframe for reserving a radio resource in which the terminal 102transmits a sounding reference signal SRS, and the bandwidth of theradio resource reserved for the transmission of the SRS in the soundingsubframe, generates information concerning the configuration as systeminformation, and broadcasts and transmits the system information on thePDSCH through the transmitting unit 507. The SRS configuration unit 5013also configures the subframe and frequency band in which a periodic SRSis periodically transmitted to each terminal 102, and the value ofcyclic shift used for CAZAC sequences of the periodic SRS, generates asignal including information concerning the configuration as a radioresource control signal (RRC signal), and notifies each mobile stationdevice 102 of the radio resource control signal on the PDSCH through thetransmitting unit 507.

The SRS configuration unit 5013 also configures the frequency band inwhich an aperiodic SRS is transmitted to each terminal 102, and thevalue of cyclic shift used for CAZAC sequences of the aperiodic SRS,generates a signal including information concerning the configuration asa radio resource control signal, and notifies each terminal 102 of theradio resource control signal on the PDSCH through the transmitting unit507. In addition, in order to request the terminal 102 to transmit theaperiodic SRS, the SRS configuration unit generates an SRS indicatorindicating that the terminal 102 is requested to transmit the aperiodicSRS, and notifies the terminal 102 of the SRS request on the PDCCHthrough the transmitting unit 507.

The transmit power configuration unit 5015 configures the transmitpowers of the PUCCH, PUSCH, periodic SRS, and aperiodic SRS.Specifically, the transmit power configuration unit 5015 configures thetransmit power of the terminal 102 in accordance with informationindicating the amount of interference from a neighboring base station,information indicating the amount of interference to a neighboring basestation 101, which has been notified by the neighboring base station,the channel quality input from the channel measurement unit 509, and soforth so that the PUSCH and the like can satisfy a certain level ofchannel quality, while taking the interference to a neighboring basestation into account. The transmit power configuration unit 5015transmits information indicating the configuration to the terminal 102through the transmitting unit 507.

More specifically, the transmit power configuration unit 5015 configuresP_(O_PUSCH) given in formula (1), which will be described below, α,P_(SRS_OFFSET(0)) for the periodic SRS (first parameter (pSRS-Offset)),and P_(SRS_OFFSET(1)): for the aperiodic SRS (second parameter(pSRS-OffsetAp-r10)), generates a signal including informationindicating the configuration as a radio resource control signal, andnotifies each terminal 102 of the radio resource control signal on thePDSCH through the transmitting unit 507. The transmit powerconfiguration unit 5015 also configures a TPC command for calculating fin formulas (1) and (4), generates a signal indicating the TPC command,and notifies each terminal 102 of the generated signal on the PDCCHthrough the transmitting unit 507. Here, α denotes a coefficient usedfor the calculation of the transmit power in formulas (1) and (4)together with the path loss value and representing the degree to whichthe path loss is compensated for, or, in other words, a coefficient todetermine the degree to which power is to be increased or decreased inaccordance with the path loss. The coefficient α generally takes a valuefrom 0 to 1. If the coefficient α is 0, power compensation is notperformed in accordance with the path loss. If the coefficient α is 1,the transmit power of the terminal 102 is increased or decreased so asto reduce the effect of the path loss on the base station 101.

The control unit 503 generates a control signal to control the receivingunit 505 and the transmitting unit 507 on the basis of the controlinformation from the higher layer processing unit 501. The control unit503 outputs the generated control signal to the receiving unit 505 andthe transmitting unit 507 to control the receiving unit 505 and thetransmitting unit 507.

The receiving unit 505 demultiplexes, demodulates, and decodes areceived signal received from the terminal 102 through thetransmit/receive antenna 511 in accordance with the control signal inputfrom the control unit 503, and outputs the decoded information to thehigher layer processing unit 501. The radio receiving unit 5057 converts(down-converts) an uplink signal received through the transmit/receiveantenna 511 into an intermediate-frequency (IF) signal, removes theunnecessary frequency component, controls the amplification level sothat the signal level can be appropriately maintained, performsorthogonal demodulation based on the in-phase component and quadraturecomponent of the received signal, and converts an analog signal obtainedby orthogonal demodulation into a digital signal. The radio receivingunit 5057 removes the portion corresponding to the guard interval (GI)from the digital signal obtained by conversion. The radio receiving unit5057 performs a fast Fourier transform (FFT) on the signal from whichthe guard interval has been removed to extract the signal of thefrequency domain, and outputs the extracted signal to the demultiplexingunit 5055.

The demultiplexing unit 5055 demultiplexes the signal input from theradio receiving unit 5057 into signals such as PUCCH, PUSCH, UL DMRS,and SRS. This demultiplexing operation is based on radio resourceallocation information that has been determined in advance by the basestation 101 and that each terminal 102 has been notified of by the basestation 101. The demultiplexing unit 5055 further performs channelcompensation of the PUCCH and PUSCH from estimated channel values inputfrom the channel measurement unit 509. The demultiplexing unit 5055outputs the UL DMRS and SRS obtained by demultiplexing to the channelmeasurement unit 509.

The demodulation unit 5053 performs an inverse discrete Fouriertransform (IDFT) on the PUSCH to acquire modulation symbols, andperforms demodulation on the received signal to demodulate each of themodulation symbols of the PUCCH and PUSCH using a predeterminedmodulation scheme such as binary phase shift keying (BPSK), quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM) or using a modulationscheme that the base station 101 has notified each terminal 102 of inadvance using downlink control information.

The decoding unit 5051 decodes the demodulated PUCCH and PUSCH code bitswith a predetermined coding rate of a predetermined coding scheme orwith a coding rate that the base station 101 has notified the terminal102 of in advance using an uplink grant (UL grant), and outputs decodeddata information and uplink control information to the higher layerprocessing unit 501.

The channel measurement unit 509 measures estimated channel values,channel quality, and so forth from the demodulated uplink referencesignals UL DMRS and SRS input from the demultiplexing unit 5055, andoutputs the results to the demultiplexing unit 5055 and the higher layerprocessing unit 501.

The transmitting unit 507 generates a reference signal for the downlink(a downlink reference signal) in accordance with the control signalinput from the control unit 503, codes and modulates the datainformation and downlink control information input from the higher layerprocessing unit 501, multiplexes the PDCCH, the PDSCH, and the downlinkreference signal, and transmits the signals to the terminal 102 throughthe transmit/receive antenna 511.

The coding unit 5071 codes the downlink control information and datainformation input from the higher layer processing unit 501 using codessuch as turbo codes, convolutional codes, or block codes. The modulationunit 5073 modulates the coded bits using a modulation scheme such asQPSK, 16QAM, or 64QAM. The downlink reference signal generation unit5079 generates a sequence known by the terminal 102, which is determinedin accordance with a predetermined rule on the basis of a cellidentifier (Cell ID) or the like for identifying the base station 101,as a downlink reference signal. The multiplexing unit 5075 multiplexesthe respective modulated channels and the generated downlink referencesignal.

The radio transmitting unit 5077 performs an inverse fast Fouriertransform (IFFT) on the multiplexed modulation symbols to perform OFDMmodulation, and adds a guard interval to the OFDM modulated OFDM symbolsto generate a baseband digital signal. Then, the radio transmitting unit5077 converts the baseband digital signal into an analog signal,generates the intermediate-frequency in-phase component and quadraturecomponent from the analog signal, removes the extra frequency componentfor the intermediate frequency band, converts (up-converts) theintermediate-frequency signal into a high-frequency signal, removes theextra frequency component, amplifies the power, and outputs theresulting signal to the transmit/receive antenna 511 for transmission.Although not illustrated here, the RRH 103 is also considered to have asimilar configuration to the base station 101.

FIG. 6 is a schematic block diagram illustrating a configuration of theterminal 102 according to this embodiment. As illustrated in FIG. 6, theterminal 102 includes a higher layer processing unit 601, a control unit603, a receiving unit 605, a transmitting unit 607, a channelmeasurement unit 609, and a transmit/receive antenna 611. The higherlayer processing unit 601 includes a radio resource control unit 6011,an SRS control unit 6013, and a transmit power control unit 6015. Thereceiving unit 605 includes a decoding unit 6051, a demodulation unit6053, a demultiplexing unit 6055, and a radio receiving unit 6057. Thetransmitting unit 607 includes a coding unit 6071, a modulation unit6073, a multiplexing unit 6075, and a radio transmitting unit 6077.

The higher layer processing unit 601 outputs uplink data informationgenerated by user operation or the like to the transmitting unit. Thehigher layer processing unit 601 further performs processing of thepacket data convergence protocol layer, the radio link control layer,and the radio resource control layer.

The radio resource control unit 6011 included in the higher layerprocessing unit 601 manages various types of configuration informationon the terminal 102. The radio resource control unit 6011 furthergenerates information to be mapped to each channel in the uplink, andoutputs the generated information to the transmitting unit 607. Theradio resource control unit 6011 generates control information tocontrol the receiving unit 605 and the transmitting unit 607 on thebasis of the downlink control information notified by the base station101 on the PDCCH and the various types of configuration information onthe terminal 102, which is managed by the radio resource control unit6011 and is configured (or is set) using the radio resource controlinformation notified on the PDSCH, and outputs the control informationto the control unit 603.

The SRS control unit 6013 included in the higher layer processing unit601 acquires, from the receiving unit 605, the information indicating asounding subframe (SRS subframe, SRS transmission subframe), which is asubframe for reserving a radio resource in which the SRS broadcasted bythe base station 101 is transmitted, and the bandwidth of the radioresource reserved for the transmission of SRS in the sounding subframe,information indicating the subframe and frequency band in which theperiodic SRS that the terminal 102 has been notified of by the basestation 101 is transmitted, and the value of cyclic shift used for CAZACsequences of the periodic SRS, and information indicating the frequencyband in which the aperiodic SRS that the terminal 102 has been notifiedof by the base station 101 is transmitted and the value of cyclic shiftused for CAZAC sequences of the aperiodic SRS.

The SRS control unit 6013 controls SRS transmission in accordance withthe pieces of information described above. Specifically, the SRS controlunit 6013 controls the transmitting unit 607 to transmit the periodicSRS once or periodically in accordance with the information concerningthe periodic SRS. In addition, in response to a request to transmit theaperiodic SRS in an SRS indicator (SRS request) input from the receivingunit 605, the SRS control unit 6013 transmits the aperiodic SRS apredetermined number of times (for example, once) in accordance with theinformation concerning the aperiodic SRS.

The transmit power control unit 6015 included in the higher layerprocessing unit 601 outputs control information to the control unit 603to perform transmit power control on the basis of information indicatingthe configuration of the transmit powers of the PUCCH, PUSCH, periodicSRS, and aperiodic SRS. Specifically, the transmit power control unit6015 individually controls the transmit power of the periodic SRS andthe transmit power of the aperiodic SRS from formula (4) on the basis ofP_(O_PUSCH), α, P_(SRS_OFFSET(0)) for the periodic SRS (first parameter(pSRS-Offset)), P_(SRS_OFFSET(1)) for the aperiodic SRS (secondparameter (pSRS-OffsetAp-r10)), and TPC commands, which are acquiredfrom the receiving unit 605. The transmit power control unit 6015switches parameters for P_(SRS_OFFSET) in accordance with the periodicSRS or the aperiodic SRS.

The control unit 603 generates a control signal to control the receivingunit 605 and the transmitting unit 607 on the basis of the controlinformation from the higher layer processing unit 601. The control unit603 outputs the generated control signal to the receiving unit 605 andthe transmitting unit 607 to control the receiving unit 605 and thetransmitting unit 607.

The receiving unit 605 demultiplexes, demodulates, and decodes areceived signal received from the base station 101 through thetransmit/receive antenna 611 in accordance with the control signal inputfrom the control unit 603, and outputs the decoded information to thehigher layer processing unit 601.

The radio receiving unit 6057 converts (down-converts) a downlink signalreceived through each receive antenna into an intermediate-frequencysignal, removes the unnecessary frequency component, controls theamplification level so that the signal level can be appropriatelymaintained, performs orthogonal demodulation based on the in-phasecomponent and quadrature component of the received signal, and convertsan analog signal obtained by orthogonal demodulation into a digitalsignal. The radio receiving unit 6057 removes the portion correspondingto the guard interval from the digital signal obtained by conversion,and performs a fast Fourier transform on the signal from which the guardinterval has been removed to extract the signal of the frequency domain.

The demultiplexing unit 6055 demultiplexes the extracted signal into aphysical downlink control channel PDCCH, a PDSCH, and a downlinkreference signal DRS. This demultiplexing operation is based on radioresource allocation information or the like notified using the downlinkcontrol information. The demultiplexing unit 6055 further performschannel compensation of the PDCCH and PDSCH from estimated channelvalues input from the channel measurement unit 609. The demultiplexingunit 6055 outputs the downlink reference signal obtained bydemultiplexing to the channel measurement unit 609.

The demodulation unit 6053 demodulates the PDCCH using a QPSK modulationscheme, and outputs the demodulated PDCCH to the decoding unit 6051. Thedecoding unit 6051 attempts to decode the PDCCH, and outputs the decodeddownlink control information to the higher layer processing unit 601 ifdecoding is successful. The demodulation unit 6053 demodulates the PDSCHusing a modulation scheme notified using the downlink controlinformation, such as QPSK, 16QAM, or 64QAM, and outputs the demodulatedPDSCH to the decoding unit 6051. The decoding unit 6051 performsdecoding with a coding rate notified using the downlink controlinformation, and outputs the decoded data information to the higherlayer processing unit 601.

The channel measurement unit 609 measures a downlink path loss from thedownlink reference signal input from the demultiplexing unit 6055, andoutputs the measured path loss to the higher layer processing unit 601.The channel measurement unit 609 further calculates estimated channelvalues for the downlink from the downlink reference signal, and outputsthe resulting values to the demultiplexing unit 6055.

The transmitting unit 607 generates an UL DMRS and/or an SRS inaccordance with the control signal input from the control unit 603,codes and modulates the data information input from the higher layerprocessing unit 601, multiplexes the PUCCH, the PUSCH, and the generatedUL DMRS and/or SRS, adjusts the transmit powers of the PUCCH, PUSCH, ULDMRS, and SRS, and transmits the results to the base station 101 throughthe transmit/receive antenna 611.

The coding unit 6071 codes the uplink control information and datainformation input from the higher layer processing unit 601 using codessuch as turbo codes, convolutional codes, or block codes. The modulationunit 6073 modulates the coded bits input from the coding unit 6071 usinga modulation scheme such as BPSK, QPSK, 16QAM, or 64QAM.

The uplink reference signal generation unit 6079 generates a CAZACsequence known by the base station 101, which is determined inaccordance with a predetermined rule on the basis of a cell identifierfor identifying the base station 101, the bandwidth within which the ULDMRS and SRS are arranged, and so forth. The uplink reference signalgeneration unit 6079 further applies a cyclic shift to the generatedCAZAC sequences of the UL DMRS and SRS in accordance with the controlsignal input from the control unit 603.

The multiplexing unit 6075 rearranges the modulation symbols of thePUSCH into parallel streams in accordance with the control signal inputfrom the control unit 603, and then performs a discrete Fouriertransform (DFT) to multiplex the PUCCH and PUSCH signals with thegenerated UL DMRS and SRS.

The radio transmitting unit 6077 performs an inverse fast Fouriertransform on the multiplexed signals to perform SC-FDMA modulation, andadds a guard interval to the SC-FDMA modulated SC-FDMA symbols togenerate a baseband digital signal. Then, the radio transmitting unit6077 converts the baseband digital signal into an analog signal,generates the intermediate-frequency in-phase component and quadraturecomponent from the analog signal, removes the extra frequency componentfor the intermediate frequency band, converts (up-converts) theintermediate-frequency signal into a high-frequency signal, removes theextra frequency component, amplifies the power, and outputs theresulting signal to the transmit/receive antenna 611 for transmission.

FIG. 7 is a diagram illustrating an example of channels used for mappingat the base station 101. FIG. 7 depicts a case where the width of afrequency band composed of 12 resource block pairs is used as the systembandwidth. A PDCCH, which is the first control channel, is arranged onthe first three OFDM symbols in a subframe. The frequency domain of thefirst control channel extends over the system bandwidth. A sharedchannel is arranged on the OFDM symbols other than those for the firstcontrol channel in the subframe.

The details of the configuration of the PDCCH will now be described. ThePDCCH is composed of a plurality of control channel elements (CCEs). Thenumber of CCEs used on each downlink component carrier depends on thedownlink component carrier bandwidth, the number of OFDM symbolsincluded in the PDCCH, and the number of downlink reference signaltransmission ports corresponding to the number of transmit antennas atthe base station 101 for use in communication. Each CCE is composed of aplurality of downlink resource elements (a resource defined by one OFDMsymbol and one subcarrier).

The CCEs used between the base station 101 and the terminal 102 areassigned numbers to identify the respective CCEs. The numbering of theCCEs is based on a predetermined rule. Here, CCE_t denotes the CCE withCCE number t. The PDCCH is constituted by an aggregation of a pluralityof CCEs (CCE Aggregation). The number of CCEs in this aggregation isreferred to as the “CCE aggregation level.” The CCE aggregation level ofthe PDCCH is set by the base station 101 in accordance with a codingrate configured for the PDCCH and the number of bits of the DCI includedin the PDCCH. A combination of CCE aggregation levels that can bepossibly used for the terminal 102 is determined in advance. Anaggregation of n CCEs is referred to as the “CCE aggregation level n.”

One resource element group (REG) is composed of four neighboringdownlink resource elements in the frequency domain. Each CCE is composedof nine different resource element groups that are scattered in thefrequency domain and the time domain. Specifically, all the resourceelement groups assigned numbers on the entire downlink component carrierare interleaved using a block interleaver in units of resource elementgroups, and nine interleaved resource element groups having consecutivenumbers constitute one CCE.

Each terminal 102 has configured therein a search space SS in which aPDCCH is searched for. Each SS is composed of a plurality of CCEs. EachSS includes a plurality of CCEs having consecutive numbers, startingfrom the smallest number, and the number of CCEs with consecutivenumbers is determined in advance. An SS for each CCE aggregation levelis composed of an aggregate of a plurality of PDCCH candidates. SSs areclassified into a CSS (Cell-specific SS) including CCEs with numberscommon in a cell, starting from the smallest number, and USS(UE-specific SS) including CCEs with numbers which are UE-specific,starting from the smallest number. In the CSS, a PDCCH to which controlinformation to be read by a plurality of terminals 102, such as systeminformation or information concerning paging, is assigned, or a PDCCH onwhich a downlink/uplink grant indicating instructions for a fallback toa low-level transmission scheme or for random access is assigned can bearranged.

The base station 101 transmits a PDCCH using one or more CCEs in an SSconfigured in the terminal 102. The terminal 102 decodes a receivedsignal using the one or more CCEs in the SS, and performs processing fordetecting the PDCCH addressed thereto (referred to as blind decoding).The terminal 102 configures a different SS for each CCE aggregationlevel. Then, the terminal 102 performs blind decoding using apredetermined combination of CCEs in a different SS for each CCEaggregation level. In other words, the terminal 102 performs blinddecoding on each of the PDCCH candidates in a different SS for each CCEaggregation level. The above-described series of processing operationsperformed in the terminal 102 is referred to as PDCCH monitoring.

The second control channel (X-PDCCH, PDCCH on PDSCH, Extended PDCCH,Enhanced PDCCH, E-PDCCH) is arranged on OFDM symbols other than thosefor the first control channel. The second control channel and the sharedchannel are arranged on different resource blocks. The resource blockson which the second control channel and the shared channel may bearranged are configured for each terminal 102. In the resource block onwhich the second control channel region may be arranged, the sharedchannel (data channel) directed to the terminal 102 or another terminalmay be configured. The starting position for the OFDM symbols on whichthe second control channel is to be arranged can be determined using amethod similar to that for the shared channel. More specifically, thebase station 101 can determine the starting position by configuring someresources in the first control channel as a PCFICH (Physical controlformat indicator channel) and mapping information indicating the numberof OFDM symbols for the first control channel.

The starting position for the OFDM symbols on which the second controlchannel is to be arranged may be defined in advance, and may be set to,for example, the fourth OFDM symbol from the beginning in the subframe.In this case, if the number of OFDM symbols for the first controlchannel is less than or equal to 2, the second to third OFDM symbols inthe resource block pair in which the second control channel is to bearranged are set to null without being mapped with signals. Othercontrol signals or data signals can further be mapped to the resourcesset to null. The starting position for the OFDM symbols included in thesecond control channel may also be configured using higher-layer controlinformation. The subframe illustrated in FIG. 7 is time-multiplexed, andthe second control channel can be configured for each subframe.

Similarly to the PDCCH, an SS in which an X-PDCCH is searched for can becomposed of a plurality of CCEs. Specifically, a plurality of resourceelements in a region configured as the region of the second controlchannel illustrated in FIG. 7 constitute a resource element group, and,in addition, a plurality of resource elements constitute a CCE.Accordingly, similarly to the case of the PDCCH described above, an SSin which an X-PDCCH is searched for (monitored) can be formed.

Alternatively, unlike the PDCCH, an SS in which an X-PDCCH is searchedfor may be composed of one or more resource blocks. Specifically, an SSin which an X-PDCCH is searched for is composed of an aggregation of oneor more resource blocks (RB Aggregation), each resource block beingincluded in a region configured as the region of the second controlchannel illustrated in FIG. 7. The number of RBs in this aggregation isreferred to as the “RB aggregation level.” An SS is composed of aplurality of RBs with consecutive numbers, starting from the smallestnumber, and the number of one or more RBs with consecutive numbers isdetermined in advance. An SS for each RB aggregation level is composedof an aggregate of a plurality of X-PDCCH candidates.

The base station 101 transmits an X-PDCCH using one or more RBs in an SSconfigured in the terminal 102. The terminal 102 decodes a receivedsignal using the one or more RBs in the SS, and performs processing fordetecting the X-PDCCH addressed thereto (performs blind decoding). Theterminal 102 configures a different SS for each RB aggregation level.Then, the terminal 102 performs blind decoding using a predeterminedcombination of RBs in a different SS for each RB aggregation level. Inother words, the terminal 102 performs blind decoding on each of theX-PDCCH candidates in a different SS for each RB aggregation level(monitors the X-PDCCH).

In a case where the base station 101 is to notify the terminal 102 of acontrol signal on the second control channel, the base station 101configures the monitoring of the second control channel with theterminal 102, and maps the control signal for the terminal 102 to thesecond control channel. In a case where the base station 101 is tonotify the terminal 102 of a control signal on the first controlchannel, the base station 101 maps the control signal for the terminal102 to the first control channel without configuring the monitoring ofthe second control channel with the terminal 102.

On the other hand, in a case where the monitoring of the second controlchannel is configured by the base station 101, the terminal 102 performsblind decoding on the control signal directed to the terminal 102 forthe second control channel. In a case where the monitoring of the secondcontrol channel is not configured by the base station 101, the terminal102 does not perform blind decoding on the control signal directed tothe terminal 102 for the second control channel.

Hereinafter, a description will be given of the control signal to bemapped to the second control channel. The control signal to be mapped tothe second control channel is processed for each piece of controlinformation on one terminal 102, and is subjected to processing such as,similarly to a data signal, scrambling processing, modulationprocessing, layer mapping processing, and precoding processing. Further,the control signal to be mapped to the second control channel issubjected to precoding processing specific to the terminal 102 togetherwith the UE-specific reference signal. Preferably, the precodingprocessing is performed with precoding weights suitable for the terminal102. For example, common precoding processing is performed on a signalfor the second control channel and a UE-specific reference signal in thesame resource block.

Furthermore, the control signal to be mapped to the second controlchannel can be mapped in such a manner that a front slot (first slot)and a rear slot (second slot) in a subframe include different pieces ofcontrol information. For example, a control signal including informationon the allocation of a data signal on the downlink shared channel(downlink allocation information), which is transmitted from the basestation 101 to the terminal 102, is mapped to the front slot in thesubframe. Then, a control signal including information on the allocationof a data signal on the uplink shared channel (uplink allocationinformation), which is transmitted from the terminal 102 to the basestation 101, is mapped to the rear slot in the subframe. Note that acontrol signal including uplink allocation information may be mapped tothe front slot in the subframe, and a control signal including downlinkallocation information may be mapped to the rear slot in the subframe.

Alternatively, a data signal for the terminal 102 or another terminal102 may be mapped to the front slot and/or rear slot on the secondcontrol channel. A control signal for the terminal 102 or a terminal(including the terminal 102) in which the second control channel hasbeen configured may be mapped to the front slot and/or rear slot on thesecond control channel.

The base station 101 multiplexes UE-specific reference signals with thecontrol signal to be mapped to the second control channel. The terminal102 performs demodulation processing on the control signal to be mappedto the second control channel, by using the UE-specific referencesignals to be multiplexed. The UE-specific reference signals for some orall of antenna ports 7 to 14 are used. In this case, the control signalto be mapped to the second control channel can be MIMO-transmitted usinga plurality of antenna ports.

For example, the UE-specific reference signal on the second controlchannel is transmitted using a predefined antenna port and a scramblingcode. Specifically, the UE-specific reference signal on the secondcontrol channel is generated using antenna port 7, which is defined inadvance, and a scrambling ID.

In addition, for example, the UE-specific reference signal on the secondcontrol channel is generated using an antenna port and a scrambling IDwhich are notified via RRC signaling or PDCCH signaling. Specifically,either antenna port 7 or antenna port 8 is notified as the antenna portto be used for the UE-specific reference signal on the second controlchannel via RRC signaling or PDCCH signaling. Any value of 0 to 3 isnotified as the scrambling ID to be used for the UE-specific referencesignal on the second control channel via RRC signaling or PDCCHsignaling.

In the first embodiment, the base station 101 configures the secondmeasurement target configuration for each terminal 102. The terminal 102sets the first measurement target configuration, and reports thereceived power of the cell-specific reference signal as the measurementtarget specified in the first measurement target configuration and thereceived power of the channel-state information reference signal as themeasurement target specified in the second measurement targetconfiguration to the base station 101.

Accordingly, the following advantages can be achieved by using thisembodiment of the claimed invention: The cell-specific reference signalsillustrated in FIG. 2 are transmitted only from the base station 101using the downlink 105. In addition, the measurement target configuredin the second measurement target configuration and the second reportconfiguration configured in step S403 in FIG. 4 is the channel-stateinformation reference signals illustrated in FIG. 3. For thismeasurement target, it is assumed that the reference signals have beentransmitted only from the RRH 103 using the downlink 107. In this case,the received signal power of the cell-specific reference signal as themeasurement target specified in the predetermined first measurementtarget configuration in step S405 in FIG. 4 and the received signalpower of the channel-state information reference signals transmittedonly from the RRH 103, which are the measurement target specified in thesecond measurement target configuration configurable by the base station101, can be measured to compute a path loss 1, which is a downlink pathloss between the base station 101 and the terminal 102, and a path loss2, which is a downlink path loss between the RRH 103 and the terminal102.

That is, whereas it is possible to configure two types of uplinktransmit power, it is possible to configure the uplink transmit powerfor one of the base station 101 and the RRH 103 (having, for example, alower path loss, that is, one of the base station 101 and the RRH 103that is closer to the terminal 102) during uplink coordinatedcommunication. In this embodiment of the claimed invention, the receivedsignal power of the cell-specific reference signal as the firstmeasurement target described above and the received signal power of thechannel-state information reference signal transmitted only from the RRH103, which is the second measurement target, are reported to the basestation 101. Accordingly, the base station 101 can judge (determine)whether an uplink signal from the terminal 102 is to be received by thebase station 101 using the uplink 106 or an uplink signal from theterminal 102 is to be received by the RRH 103 using the uplink 108during uplink coordinated communication. Based on this judgment, thebase station 101 can configure parameters related to uplink powercontrol in FIG. 3, and can configure which of the path loss 1 and thepath loss 2, described above, is to be used.

In another example, it is assumed that: the cell-specific referencesignals illustrated in FIG. 2 are transmitted from the base station 101and the RRH 103 using the downlink 105 and the downlink 106; twomeasurement targets are configured in the second measurement targetconfiguration and second report configuration configured in step S403 ofFIG. 4; both the configured measurement targets are the channel-stateinformation reference signals illustrated in FIG. 3; and a referencesignal has been transmitted only from the base station 101 using thedownlink 105 as one of the measurement targets whereas a referencesignal has been transmitted only from the RRH 103 using the downlink 107as the other measurement target. In this case, the received signal powerof the cell-specific reference signal as the first measurement targetspecified in the predetermined first measurement target configuration instep S405 in FIG. 4, the received signal power of the channel-stateinformation reference signal transmitted only from the base station 101,which is one of second measurement targets that are the measurementtargets specified in the second measurement target configurationconfigurable by the base station 101, and the received signal power ofthe channel-state information reference signal transmitted only from theRRH 103, which is one of the second measurement targets, can be measuredto compute a path loss 1, which is the combined value of the downlinkpath loss between the base station 101 and the terminal 102 and thedownlink path loss between the RRH 103 and the terminal 102, and a pathloss 2 including the downlink path loss value between the base station101 and the terminal 102 and the downlink path loss value between theRRH 103 and the terminal 102.

That is, whereas the terminal 102 can configure two types of uplinktransmit power, the terminal 102 can configure the uplink transmit powerfor one of the base station 101 and the RRH 103 (having, for example, alower path loss, that is, one of the base station 101 and the RRH 103that is closer to the terminal 102) during uplink coordinatedcommunication. In this embodiment of the claimed invention, the receivedsignal power of the cell-specific reference signal as the firstmeasurement target described above, the received signal power of thechannel-state information reference signal transmitted only from thebase station 101, which is a second measurement target, and the receivedsignal power of the channel-state information reference signaltransmitted only from the RRH 103, which is the other second measurementtarget, are reported to the base station 101. Accordingly, the basestation 101 can determine whether an uplink signal from the terminal 102is to be received by the base station 101 using the uplink 106 or anuplink signal from the terminal 102 is to be received by the RRH 103using the uplink 108 during uplink coordinated communication. Based onthis determination, the base station 101 can configure parametersrelated to uplink power control in FIG. 3, and can configure which ofthe three path losses, namely, the path loss 1 and the two path losses 2described above, is to be used.

In this embodiment of the claimed invention, furthermore, the terminal102 can perform transmit power control suitable for uplink coordinatedcommunication by computing the uplink transmit power using the path loss1, which is the combined value of the downlink path loss between thebase station 101 and the terminal 102 and the downlink path loss betweenthe RRH 103 and the terminal 102. Additionally, the terminal 102 canperform transmit power control suitable for communication between thebase station 101 and the terminal 102 by computing the uplink transmitpower using the path loss 2 based on the second measurement targetbetween the base station 101 and the terminal 102. In addition, theterminal 102 can perform transmit power control suitable forcommunication between the RRH 103 and the terminal 102 by computing theuplink transmit power using the path loss 2 based on the secondmeasurement target between the RRH 103 and the terminal 102. In thismanner, with the use of both the predetermined first measurementconfiguration and the second measurement target configurationconfigurable by the base station 101, appropriate uplink power controlcan be performed regardless of the configuration of the referencesignals from the base station 101 and the RRH 103 (for example, in acase where the cell-specific reference signal is transmitted from thebase station 101 or in a case where the cell-specific reference signalis transmitted from both the base station 101 and the RRH 103). In thisembodiment, furthermore, reporting the received signal power of thecell-specific reference signal specified in the first measurement targetconfiguration and the received signal power of the channel-stateinformation reference signal specified in the second measurement targetconfiguration helps the base station 101 understand the positionalrelationship (i.e., expected received power or path loss) between thebase station 101, the RRH 103, and the terminal 102, which also makesadvantages feasible during downlink coordinated communication. Forexample, if the downlinks 105 and 106 are used, a signal received by theterminal 102 is transmitted from the base station 101, the RRH 103, orboth the base station 101 and the RRH 103, which is appropriatelyselected. Thus, the throughput of the entire system is expected toincrease as a result of suppressing unwanted signal transmission.

Second Embodiment

A second embodiment of the present invention will be describedhereinafter. The description of this embodiment will be directed to thedetails of the parameter configuration of a channel-state informationreference signal, the second measurement target configuration, secondreport configuration, third measurement target configuration, and thirdreport configuration in step S403 in FIG. 4, and the parameters relatedto the first measurement report and the second measurement report instep S407 in FIG. 4. A description will also be given here of thedetails of a first reference signal configuration for CSI feedbackcalculation, a second reference signal configuration for specifying aresource element to be excluded from the target of data demodulationwhen data is demodulated, and a third reference signal configuration forconfiguring a measurement target for calculating a received signalpower.

In FIG. 8, the details of the parameters related to the first referencesignal configuration and the second reference signal configuration areillustrated as the details of a channel-state information referencesignal. CSI-RS configuration-r10 (CSI-RS-Config-r10) may include aCSI-RS configuration, that is, a first reference signal configuration(csi-RS-r10), and a zero transmit power CSI-RS configuration, that is, asecond reference signal configuration (zeroTxPowerCSI-RS-r10). TheCSI-RS configuration may include an antenna port(antennaPortsCount-r10), a resource configuration (resourceConfig-r10),a subframe configuration (subframeConfig-r10), and a PDSCH/CSI-RS powerconfiguration (p-C-r10).

The antenna port (antennaPortsCount-r10) specifies the number of antennaports reserved in the CSI-RS configuration. In an example, any of thevalues 1, 2, 4, and 8 is selected in the antenna port(antennaPortsCount-r10). In the resource configuration(resourceConfig-r10), the position of the top resource element (minimumblock defined by frequency (subcarrier) and time (OFDM symbol)illustrated in FIGS. 2 and 3) for antenna port 15 (CSI port 1) isrepresented by an index. Accordingly, the resource elements of thechannel-state information reference signals allocated to the respectiveantenna ports are uniquely determined. The details will be describedbelow.

In the subframe configuration (subframeConfig-r10), the position andinterval of a subframe including the channel-state information referencesignal is represented by an index. For example, if an index in thesubframe configuration (subframeConfig-r10) is 5, the channel-stateinformation reference signal is included every ten subframes and thechannel-state information reference signal is included in subframe 0 ina radio frame having ten subframes as a unit. In another example, forexample, if an index in the subframe configuration (subframeConfig-r10)is 1, the channel-state information reference signal is included everyfive subframes and the channel-state information reference signal isincluded in subframes 1 and 6 in a radio frame having ten subframes usedas a unit. In the way described above, the subframe configurationuniquely specifies the interval and the position of a subframe includingthe channel-state information reference signal.

The PDSCH/CSI-RS power configuration (p-C-r10) specifies the power ratioof the PDSCH to the channel-state information reference signal (CSI-RS)(the ratio of EPRE: Energy Per Resource Element), and may be configuredin the range from −8 to 15 dB. Although not illustrated here, the basestation 101 separately notifies the terminal 102 of cell-specificreference signal transmit power (referenceSignalPower), P_(A), andP_(B), using RRC signals. Here, P_(A) denotes an index representing thetransmit power ratio of the PDSCH to the cell-specific reference signalin a subframe not including the cell-specific reference signal, andP_(B) denotes an index representing the transmit power ratio of thePDSCH to the cell-specific reference signal in a subframe including thecell-specific reference signal. Combining the PDSCH/CSI-RS powerconfiguration (p-C-r10), the cell-specific reference signal transmitpower (referenceSignalPower), and P_(A) allows the terminal 102 tocalculate the transmit power of the channel-state information referencesignal.

An example of the resource configuration (resourceConfig-r10) will nowbe given. In the resource configuration (resourceConfig-r10), theposition of a resource allocated to the CSI-RS for each antenna port isrepresented by an index. For example, if index 0 is specified in theresource configuration (resourceConfig-r10), the top resource elementfor antenna port 15 (CSI port 1) is designated as subcarrier number 9and subframe number 5. As illustrated in FIG. 3, C1 is allocated toantenna port 15. Accordingly, the resource element with subcarriernumber 9 and subframe number 6 is also configured as the channel-stateinformation reference signal for antenna port 15 (CSI port 1). Based onthis configuration, the resource elements for the respective antennaports are also reserved. For example, the resource element withsubcarrier number 9 and subframe number 5 and the resource element withsubcarrier number 9 and subframe number 6 are allocated to antenna port16 (CSI port 2).

Similarly, the resource element with subcarrier number 3 and subframenumber 5 and the resource element with subcarrier number 3 and subframenumber 6 are allocated to antenna ports 17 and 18 (CSI ports 3 and 4).Similarly, the resource element with subcarrier number 8 and subframenumber 5 and the resource element with subcarrier number 8 and subframenumber 6 are allocated to antenna ports 19 and 20 (CSI ports 5 and 6).Similarly, the resource element with subcarrier number 2 and subframenumber 5 and the resource element with subcarrier number 2 and subframenumber 6 are allocated to antenna ports 21 and 22 (CSI ports 7 and 8).If any other index is specified in the resource configuration(resourceConfig-r10), the top resource element for antenna port 15 (CSIport 1) is differently configured, and the resource elements allocatedto the respective antenna ports are also different accordingly.

The zero transmit power CSI-RS configuration (second reference signalconfiguration) may include a zero transmit power resource configurationlist (zeroTxPowerResourceConfigList-r10) and a zero transmit powersubframe (zeroTxPowerSubframeConfig-r10) configuration. In the zerotransmit power resource configuration list, one or a plurality ofindexes included in the resource configuration (resourceConfig-r10)described above are specified by bitmap. In the zero transmit powersubframe configuration, as described above, the position and interval ofa subframe including the channel-state information reference signal isrepresented by an index.

Accordingly, appropriate configuration of the zero transmit powerresource configuration list and the zero transmit power subframeconfiguration allows the terminal 102 to specify a resource element tobe excluded from the target of demodulation processing when demodulatingthe PDSCH (downlink shared channel, downlink data channel, downlink datasignal, Physical Downlink Shared Channel) as a resource of thechannel-state information reference signal. By way of example, the indexspecified in the zero transmit power resource configuration listsupports the resource configuration (resourceConfig-r10) for fourantenna ports (antennaPortsCount-r10). In other words, the resourceconfiguration (resourceConfig-r10) is notified by 16 indexes in the caseof four antenna ports. Accordingly, the zero transmit power resourceconfiguration list specifies a 16-bit bitmap to make notification of theresources of the channel-state information reference signals representedby the 16 indexes described above. For example, if indexes 0 and 2 arenotified by bitmap, the resource elements corresponding to indexes 0 and2 are excluded from the target of demodulation processing whendemodulation is performed.

Now, the details of the parameters related to the second measurementtarget configuration in step S403 in FIG. 4 will be described withreference to FIG. 9. The reference signal measurement configuration inFIG. 9, that is, the third reference signal configuration or the secondmeasurement target configuration, may include a reference signalmeasurement configuration-addition/modification list and a referencesignal measurement configuration-removal list. The reference signalmeasurement configuration-addition/modification list may include aCSI-RS measurement index and a CSI-RS measurement configuration. Thereference signal measurement configuration-removal list may include aCSI-RS measurement index. The CSI-RS measurement index and the CSI-RSmeasurement configuration are configured in combination, and one or aplurality of combinations each including a CSI-RS measurement index anda CSI-RS measurement configuration are configured in the referencesignal measurement configuration-addition/modification list. The CSI-RSmeasurement configuration or configurations configured in the referencesignal measurement configuration-addition/modification list are themeasurement targets. A CSI-RS measurement index is an index associatedwith a CSI-RS measurement configuration, and is an index fordistinguishing a plurality of measurement targets configured in thethird reference signal configuration from one another. In accordancewith this index, the corresponding CSI-RS measurement configuration isdeleted from the measurement target using the reference signalmeasurement configuration-removal list, or, in a measurement reportdescribed below, a measurement report and a measurement target specifiedby the index are associated with each other. The CSI-RS measurementconfiguration will be described below with reference to FIGS. 11 and 12.

In another example, as illustrated in FIG. 10, only a CSI-RS antennaport index may be configured in the reference signal measurementconfiguration-addition/modification list and the reference signalmeasurement configuration-removal list. The CSI-RS antenna port index isan index associated with each of the antenna port numbers (antenna ports15 to 22) for the channel-state information reference signal illustratedin FIG. 3. The CSI-RS antenna port index configured in the thirdreference signal configuration in FIG. 10 may be included in thechannel-state information reference signal configured in the firstreference signal configuration illustrated in FIG. 8 or may notnecessarily be included in the channel-state information referencesignal configured in the first reference signal configuration. If theCSI-RS antenna port index is not included in the channel-stateinformation reference signal configured in the first reference signalconfiguration, the third reference signal configuration targets achannel-state information reference signal if the CSI-RS antenna portindex configured in the third reference signal configuration is includedin the channel-state information reference signal configured in thefirst reference signal configuration.

Next, the details of the CSI-RS measurement configuration in FIG. 9 willbe described with reference to FIGS. 11 and 12. In an example, asillustrated in FIG. 11, the CSI-RS measurement configuration may includea measurement resource configuration list, a measurement subframeconfiguration, and a PDSCH/CSI-RS power configuration. The measurementresource configuration list and the measurement subframe configurationmay be considered to be similar to the zero transmit power resourceconfiguration list (zeroTxPowerResourceConfigList-r10) and the zerotransmit power subframe (zeroTxPowerSubframeConfig-r10) configurationillustrated in FIG. 8. The PDSCH/CSI-RS power configuration may beconsidered to be similar to the PDSCH/CSI-RS power configuration(p-C-r10) illustrated in FIG. 8. In another example, as illustrated inFIG. 12, the CSI-RS measurement configuration may include a measurementresource configuration, a measurement subframe configuration, and aPDSCH/CSI-RS power configuration. The measurement resourceconfiguration, the measurement subframe configuration, and thePDSCH/CSI-RS power configuration may be considered to be similar to theresource configuration (resourceConfig-r10), the subframe configuration(subframeConfig-r10), and the PDSCH/CSI-RS power configuration (p-C-r10)illustrated in FIG. 8. While the PDSCH/CSI-RS power configuration isassumed in FIGS. 11 and 12, CSI-RS transmit power (channel-stateinformation reference signal transmit power) may be notified instead.

Now, the details of the third measurement target configuration and thethird report configuration in step S403 in FIG. 4 will be described withreference to FIG. 13. In an example, an RRC connection reconfiguration(RRCConnectionReconfiguration) may include an RRC connectionreconfiguration-r8-IEs (RRCConnectionReconfiguration-r8-IEs), and theRRC connection reconfiguration-r8-IEs may include a measurementconfiguration (MeasConfig: Measurement Config). The measurementconfiguration may include a measurement object removal list(MeasObjectToRemoveList), a measurement object addition/modificationlist (MeasObjectToAddModList), a measurement ID removal list, ameasurement ID addition/modification list, a report configurationremoval list (ReportConfigToRemoveList), and a report configurationaddition/modification list (ReportConfigToAddModList). The thirdmeasurement target configuration illustrated in step S403 in FIG. 4 isassumed to specify the measurement object removal list, the measurementobject addition/modification list, the measurement ID removal list, andthe measurement ID addition/modification list, and the third reportconfiguration is assumed to specify the report configuration removallist and the report configuration addition/modification list. Themeasurement ID addition/modification list may include a measurement ID,a measurement object ID, and a report configuration ID, and themeasurement ID removal list may include a measurement ID. Themeasurement object ID is associated with a measurement object describedbelow, and the report configuration ID is associated with a reportconfiguration ID described below.

In the measurement object addition/modification list, as illustrated inFIG. 14, a measurement object ID and a measurement object areselectable. A measurement object can be selected from measurementobjects such as the measurement object EUTRA, the measurement objectUTRA, the measurement object GERAN, and the measurement object CDMA2000.For example, for the measurement object EUTRA, the base station 101notifies the terminal 102 of a carrier frequency (center frequency) andso forth, allowing the terminal 102 to measure the received signal powerof a cell-specific reference signal transmitted from an unconnected cell(a cell with no RRC parameters configured) (see FIG. 15). That is, thethird measurement target configuration and the third reportconfiguration allow measurement of the received signal power of acell-specific reference signal of an unconnected cell. The measurementobject removal list includes a measurement object ID. Once a measurementobject ID is specified, the associated measurement object can be deletedfrom the measurement objects. The measurement target configurationdescribed above is included in the RRC connection reconfiguration, andis thus configured using RRC signals at the time of the reconfigurationof RRC connection (RRC Connection Reconfiguration). The RRC connectionreconfiguration described above and a variety of information elements/avariety of configurations included in the RRC connection reconfigurationmay be configured for each terminal 102 using RRC signals (Dedicatedsignaling). The physical configuration described above may be configuredfor each terminal 102 using RRC messages. The RRC reconfiguration andRRC re-establishment described above may be configured for each terminal102 using RRC messages.

Now, the details of the second measurement target configuration andsecond report configuration in step S403 in FIG. 4 will be describedwith reference to FIG. 16. In an example, a dedicated physicalconfiguration (PhysicalConfigDedicated) may include a measurementconfiguration, and the measurement configuration may include ameasurement object removal list, a measurement objectaddition/modification list, a measurement ID removal list, a measurementID addition/modification list, a report configuration removal list, anda report configuration addition/modification list. The secondmeasurement target configuration illustrated in step S403 in FIG. 4specifies the measurement object removal list and the measurement objectaddition/modification list, and may further include the measurement IDremoval list and the measurement ID addition/modification list. Thesecond report configuration is assumed to specify the reportconfiguration removal list and the report configurationaddition/modification list. The measurement object removal list and themeasurement object addition/modification list given here are consideredto be similar to the reference signal measurementconfiguration-addition/modification list and the reference signalmeasurement configuration-removal list illustrated in FIG. 9 or FIG. 10.

While the dedicated physical configuration (PhysicalConfigDedicated),which is a dedicated physical configuration, is illustrated in FIG. 16,a dedicated physical configuration for the SCell(PhysicalConfigDedicatedSCell-r11), which is a dedicated physicalconfiguration allocated to a secondary cell, may be used. The dedicatedphysical configuration described above is configured using RRC signalsat the time of the re-establishment of the RRC connection (RRCConnection Reestablishment) or at the time of the reconfiguration of theRRC connection (RRC Connection Reconfigration). On the other hand, thededicated physical configuration for the SCell may be included in theSCell addition/modification list, and is configured using RRC signalswhen a SCell is added and when the configuration is modified. In thismanner, the second measurement target configuration and the secondreport configuration allow measurement of the received signal power of aconfigured channel-state information reference signal of a connectedcell. The measurement object addition/modification list and themeasurement object removal list (second measurement targetconfiguration) illustrated in FIG. 16 may be similar in content to thereference signal measurement configuration-addition/modification listand the reference signal measurement configuration-removal list (thirdreference signal configuration) illustrated in FIG. 9 or FIG. 10.

More specifically, in the measurement object addition/modification listand the measurement object removal list illustrated in FIG. 16, a thirdreference signal is configured using the CSI-RS measurementconfiguration (see FIGS. 11 and 12) identified by the CSI-RS measurementindex illustrated in FIG. 9, or a third reference signal is configuredusing the CSI-RS antenna port index illustrated in FIG. 10. While it isassumed in FIG. 16 that the dedicated physical configuration(PhysicalConfigDedicated) or the dedicated physical configuration forthe SCell (PhysicalConfigDedicatedSCell-r11), which is a dedicatedphysical configuration allocated to a secondary cell, includes thesecond measurement target configuration, the second measurement targetconfiguration may be included in the CSI-RS configuration-r10 of FIG. 8described above. In another example, it is assumed that the secondmeasurement target configuration is included. The second measurementtarget configuration may be included in the measurement configuration inFIG. 13 described above. The physical configuration described above maybe configured for each terminal using RRC signals (Dedicated signaling).

The details of the second report configuration in FIG. 16 will now bedescribed with reference to FIG. 17. In an example, the reportconfiguration-addition/modification list includes a combinationincluding a report configuration ID and a report configuration. Thereport configuration-removal list includes a report configuration ID.The report configuration-addition/modification list may include aplurality of combinations each including a report configuration ID and areport configuration or one combination including a report configurationID and a report configuration. The report configuration-removal list mayinclude a plurality of report configuration IDs or one reportconfiguration ID. As in FIG. 17, the report configurationaddition/modification list in FIG. 13 includes one or a plurality ofcombinations each including a report configuration ID and a reportconfiguration, and the content of the report configuration is similar tothat of the report configuration. The report configuration removal listin FIG. 13 also includes one or a plurality of report configuration IDs,as in FIG. 17.

The report configuration in FIG. 17 will now be described with referenceto FIG. 18. In an example, the report configuration includes a triggertype. The trigger type includes the configuration of information such asa threshold used for an event for performing reporting and a reportinterval.

Next, the configuration related to the first measurement report and thesecond measurement report in step S407 in FIG. 4, namely, a firstmeasurement report and a second measurement report list, will bedescribed with reference to FIG. 19. A dedicated control channel messagetype (UL-DCCH-MessageType) illustrated in FIG. 19 is one of the RRCmessages transmitted from a terminal to the base station 101. Thededicated control channel message type described above includes at leasta measurement report (MeasurementReport). A report included in themeasurement report is selectable. At least a first measurement report(measurement report-r8, MeasurementReport-r8-IEs) and a secondmeasurement report list can be selected. The first measurement reportmay include measurement results (MeasResults), and the measurementresults may include a measurement ID (MeasID), PCell measurement results(measResultPCell), neighbouring cell measurement results(measResultNeighCells), and a serving frequency measurement result list.A EUTRA measurement result list (MeasResultListEUTRA), a UTRAmeasurement result list (MeasResultListUTRA), a GERAN measurement resultlist (MeasResultListGERAN), or CDMA2000 measurement results(MeasResultsCDMA2000) are selectable as the neighbouring cellmeasurement results. The serving frequency measurement result list mayinclude a serving cell index, SCell measurement results, and bestneighbouring cell measurement results. While it is assumed in FIG. 19that the first measurement report and the second measurement report listare arranged in parallel and one of them is selected, the measurementresults of the first measurement report may include the secondmeasurement report.

The details of the EUTRA measurement result list illustrated in FIG. 19will now be described with reference to FIG. 20. The EUTRA measurementresult list includes a physical cell ID (PhysCellID) and a measurementresult (measResult). The physical cell ID and the measurement result areused in combination, allowing the terminal 102 to notify the basestation 101 of on which neighbouring cell the measurement information isbeing notified. The EUTRA measurement result list may include aplurality of physical cell IDs and a plurality of measurement results,or may include one physical cell ID and one measurement result. ThePCell measurement results and the serving frequency measurement resultlist included in the illustration of FIG. 19 are obtained as a result ofthe measurement of the measurement target specified in the firstmeasurement target configuration described above. The measurementresults included in the EUTRA measurement result list included in theillustration of FIG. 20 or the like are obtained as a result of themeasurement of the measurement target specified in the third measurementtarget configuration in FIG. 13.

The measurement ID illustrated in FIG. 19 represents the measurement IDillustrated in FIG. 13, and is therefore associated with the measurementobject included in the third measurement target configuration and themeasurement report configuration included in the third reportconfiguration. The relationship between the measurement report and thefirst to third measurement target configurations will now be described.The terminal 102 can report the received signal power at antenna port 0for the cell-specific reference signal of the PCell and the receivedsignal power at antenna port 0 for the cell-specific reference signal ofthe SCell to the base station 101 using the PCell measurement result andthe SCell measurement result included in the first measurement report.These are the measurement targets specified in the first measurementtarget configuration. In contrast, the terminal 102 can report thereceived signal power at antenna port 0 for the cell-specific referencesignal of a neighbouring cell to the base station 101 using a physicalcell ID and a measurement result included in the EUTRA measurementresult list. These are the measurement targets specified in the thirdmeasurement target configuration. That is, the first measurement reportand the third measurement target configuration allow the terminal 102 toreport the received signal power at antenna port 0 for the cell-specificreference signal of an unconnected cell (a cell with no RRC parametersconfigured, neighbouring cell) to the base station 101. The terminal 102to the base station 101 and the terminal 102 to the base station 101that is, the terminal 102 can report the received signal power atantenna port 0 for the cell-specific reference signal of each cell(primary cell, secondary cell, neighbouring cell) to the base station101 using the first measurement report.

The details of the second measurement report list illustrated in FIG. 19will now be described with reference to FIG. 21. The second measurementreport included in the second measurement report list includes a CSI-RSmeasurement index and a measurement result. In place of the CSI-RSmeasurement index, a CSI-RS antenna port index may be included. TheCSI-RS measurement index and the CSI-RS antenna port index, as usedhere, specify the CSI-RS measurement index and the CSI-RS antenna portindex depicted in FIGS. 9 and 10. Accordingly, the terminal 102 canreport the received signal power of the measurement target configured inthe third reference signal configuration to the base station 101 usingthe measurement results of the second measurement report. For example,in a case where antenna port 15 for the channel-state informationreference signal is specified in the third reference signalconfiguration, the terminal 102 can report the received signal power atantenna port 15 for the channel-state information reference signal tothe base station 101.

More specifically, the terminal 102 can report the received signal powerof a configured channel-state information reference signal (for example,antenna port 15 for the channel-state information reference signal,etc.) of a connected cell (primary cell, secondary cell) to the basestation 101 using the second measurement report. Although notillustrated here, an index specifying a specific cell (carriercomponent), such as a serving cell index, may be included in the secondmeasurement report illustrated in FIG. 21. In this case, the servingcell index, the CSI-RS measurement index, and the measurement resultsare used in combination, allowing the terminal 102 to report for whichchannel-state information reference signal the result of measurement hasbeen obtained and in which cell the channel-state information referencesignal is included to the base station 101.

In the second embodiment, the base station 101 configures, for eachterminal 102, a second measurement target configuration for onlymeasuring a channel information reference signal configured by the basestation 101, and configures, for each terminal 102, a third measurementtarget configuration for measuring a cell-specific reference signalgenerated using a physical ID different from the physical ID of the cellto which the terminal 102 is connected. The terminal 102 reports thereceived signal of the reference signal as the measurement targetspecified in the second measurement target configuration and thereceived signal of the reference signal as the measurement targetspecified in the third measurement target configuration to a basestation.

In the second embodiment, furthermore, the base station 101 configures,for each of the terminals, a first reference signal configuration forconfiguring a measurement target used for channel-state reporting,configures, for each terminal 102, a second reference signalconfiguration for specifying a resource element to be excluded from thetarget of data demodulation when the terminal 102 demodulates data, andconfigures, for each terminal 102, a third reference signalconfiguration for configuring a measurement target as which the terminal102 measures the received power of the reference signal. The terminal102 receives the information configured by the base station 101, reportsthe channel state to the base station 101 on the basis of the firstreference signal configuration, determines a resource element to beexcluded from the target of data demodulation when data is demodulatedon the basis of the second reference signal configuration, demodulatesthe data, and measures the reference signal received power on the basisof the third reference signal configuration.

Accordingly, the following advantages can be achieved by using theembodiment of the claimed invention described above. It is assumed thatthe cell-specific reference signals illustrated in FIG. 2 and antennaports 15, 16, 17, and 18 for the channel-state information referencesignal illustrated in FIG. 3 are transmitted only from the base station101 using the downlink 105. It is also assumed that the measurementtarget configured in the second measurement target configuration andsecond report configuration configured in step S403 in FIG. 4, that is,the measurement target configured in the third reference signalconfiguration in FIG. 9, is antenna port 19 for the channel-stateinformation reference signal illustrated in FIG. 3, and that, for thismeasurement target, the channel-state information reference signal hasbeen transmitted only from the RRH 103 using the downlink 107. In thiscase, the received signal power of the cell-specific reference signal asthe first measurement target in step S405 in FIG. 4 and the receivedsignal power of the channel-state information reference signaltransmitted only from the RRH 103, which is the second measurementtarget, can be measured to compute a path loss 1, which is the downlinkpath loss between the base station 101 and the terminal 102, and a pathloss 2, which is the downlink path loss between the RRH 103 and theterminal 102.

The first reference signal configuration is directed to antenna ports15, 16, 17, and 18. Accordingly, Rank information (Rank), precodinginformation (PMI: Precoding Matrix Indicator), and channel qualityinformation (CQI: Channel Quality Indicator) based on the firstreference signal configuration are notified and are used for theprecoding of the UE-specific reference signal and data signal and forthe modulation and coding scheme (MCS) of the data signal. In contrast,measurement and reporting of the received signal power are performed forantenna port 19 for the channel-state information reference signal asthe measurement target configured in the third reference signalconfiguration. In the communication system, accordingly, it is possibleto configure an antenna port (or measurement target) on which thereceived power (and path loss) is measured, separately from an antennaport on which communication is actually taking place in the downlink.For example, the base station 101 can reduce the frequency with which areference signal for the antenna port used for the measurement of onlythe received power is transmitted, compared to a reference signal forthe antenna port on which communication is taking place in the downlink,and can suppress an increase in the system overhead for referencesignals. Furthermore, if the received signal power at antenna port 19for the channel-state information reference signal increases (i.e., thepath loss between the RRH 103 and a terminal decreases), the basestation 101 can reconfigure the channel-state information referencesignal configured in the first reference signal configuration to anantenna port allocated to the RRH 103. Accordingly, a downlink signalcan always be transmitted from an appropriate transmission point (i.e.,the base station 101 or the RRH 103).

In another point of view, while antenna ports 15, 16, 17, and 18 for thechannel-state information reference signal configured in the firstreference signal configuration can be used for signal transmission inthe downlink, the path loss determined from antenna port 19 for thechannel-state information reference signal configured in the thirdreference signal configuration can also be used for signal transmissionin the uplink. This enables the terminal 102 to receive a downlinksignal from the base station 101 via the downlink 105 and to transmit anuplink signal to the RRH 103 using the uplink 108. In this manner, afirst reference signal configuration for configuring a measurementtarget for calculating CSI feedback including at least one of CQI, PMI,and RI, and a third reference signal configuration for configuring ameasurement target for calculating a received signal power areconfigured. In addition, at least some of the resources configured inthe third reference signal configuration are not included in theresources configured in the first reference signal configuration.Accordingly, the communication system can be flexibly designed such thatthe destinations of the downlink signal and the uplink signal arechanged.

In another point of view, it is assumed that the cell-specific referencesignals illustrated in FIG. 2 are transmitted only from the base station101 using the downlink 105. It is also assumed that the measurementtarget configured in the second measurement target configuration andsecond report configuration configured in step S403 in FIG. 4 is thechannel-state information reference signals illustrated in FIG. 3, andthat, for this measurement target, the channel-state informationreference signals have been transmitted only from the RRH 103 using thedownlink 107. It is further assumed that the base station 101 and theRRH 103 are carrying out carrier aggregation, and are performingcommunication using two carrier components (Carrier Component, CC, Cell,cell) having different center frequencies for uplink and downlink. Thesecarrier components are called a first carrier component and a secondcarrier component, and the base station 101 and the RRH 103 are assumedto be capable of individual communication and coordinated communicationby using these carrier components. In this case, the terminal 102 setsup a connection with the base station 101 via the first carriercomponent. At the same time, a measurement target is measured inaccordance with parameters related to predetermined first measurement.The measurement target is antenna port 0 for the cell-specific referencesignal of a connected cell.

At the same time, parameters related to third measurement and thirdreport are configured, and a measurement target is measured. Themeasurement target is antenna port 0 for the unconnected cell-specificreference signal. Then, in step S407 in FIG. 4, the terminal 102 reportsthe first measurement report illustrated in FIG. 19 to the base station101. That is, the received power of the cell-specific reference signaltransmitted from antenna port 0 of the connected cell described aboveand the received power of the cell-specific reference signal transmittedfrom the unconnected antenna port 0 described above are reported to thebase station 101 via the first measurement report. Meanwhile, after theconnection to the first carrier component (primary cell), a secondmeasurement configuration for the first carrier component is configuredindividually using the dedicated physical configuration, or a secondmeasurement configuration for the second carrier component is configuredwhen a second carrier component (secondary cell) is added (when thededicated physical configuration for the SCell is configured).

More specifically, whereas the third measurement target configurationallows the terminal 102 to measure antenna port 0 for the cell-specificreference signal of an unconnected cell and to report the measurementresult to the base station 101, the second measurement configuration andthe second measurement report allow the terminal 102 to measure aconfigured antenna port of a channel-state information reference signalof a connected cell and to report the measurement result to the basestation 101 via the second measurement report. Accordingly, the terminal102 and the base station 101 can search for an optimum base station 101and cell by only using the third measurement target configuration, thethird report configuration, and the first measurement report, and cansearch for an optimum transmission point (for example, the base station101 or the RRH 103) or measure the path loss on the basis of the firstmeasurement object configuration and second measurement targetconfiguration. The term connected cell, as used herein, refers to a cellwith parameters configured using RRC signals, that is, the primary cell(first carrier component) or the secondary cell (second carriercomponent), and the term unconnected cell refers to a cell with noparameters configured using RRC signals, such as a neighbouring cell. Inanother aspect, a cell-specific reference signal transmitted from anunconnected cell may be generated using a physical ID (physical cell ID)different from that of a cell-specific reference signal transmitted fromthe connected cell.

Third Embodiment

A third embodiment will now be described. The description of the thirdembodiment will be directed to the processing of step S408 to step S409in FIG. 4 in detail. Particularly, the processing of a communicationsystem in a case where parameters related to a plurality of types ofuplink power control are configured will be described in detail. Here, adetailed description will be given, in particular, of the followingexample: A path loss (first path loss) is computed based on the firstmeasurement target configuration and the uplink power control relatedparameter configuration, and a first uplink transmit power is computedbased on the first path loss and the uplink power control relatedparameter configuration. Furthermore, the terminal 102 computes a pathloss (second path loss) on the basis of the second measurement targetconfiguration and the uplink power control related parameterconfiguration, and computes a second uplink transmit power on the basisof the second path loss and the uplink power control related parameterconfiguration. That is, a detailed description will be given of theimplicit (fixed) configuration of the first measurement objectconfiguration and second measurement target configuration and the firstuplink transmit power and second uplink transmit power.

An uplink transmit power computation method will be described. Theterminal 102 determines the PUSCH uplink transmit power in a subframe iin a serving cell c using formula (1).

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack} & \; \\{{P_{{PUSCH},c}(i)} = {\min \begin{Bmatrix}{{P_{{CMAX},c}(i)},} \\\begin{matrix}{{10\; {\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O\_ PUSCH},c}(j)} +} \\{{{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix}\end{Bmatrix}}} & (1)\end{matrix}$

P_(CMAX,c) denotes the maximum transmit power in the serving cell c.M_(PUSCH,c) denotes the transmission bandwidth (the number of resourceblocks in the frequency domain) of the serving cell c. P_(O_PUSCH,c)denotes the nominal power of the PUSCH in the serving cell c.P_(O_PUSCH,c) is determined from P_(O_NOMINAL_PUSCH,c) andP_(O_UE_PUSCH,c). P_(O_NOMINAL_PUSCH,c) is a cell-specific parameterrelated to uplink power control. P_(O_UE_PUSCH,c) is a UE-specificparameter related to uplink power control. α is an attenuationcoefficient (channel loss compensation coefficient) used for thefractional transmit power control of the entire cell. PL_(c) is a pathloss which is determined from the reference signal transmitted at knownpower and from the RSRP. In the present invention, PL_(c) may be acomputational result of the path loss determined in the first embodimentor the second embodiment. Δ_(TF,c) is determined using formula (2).

[Math. 2]

Δ_(TF,c)(i)=10 log₁₀((2^(BPRE·K) ^(s) −1)·ρ_(offset) ^(PUSCH))   (2)

BPRE denotes the number of bits that can be allocated to the resourceelement. K_(s) is a parameter related to uplink power control which isnotified by the higher layer using RRC signals, and is a parameterdependent on the modulation and coding scheme (MCS) of the uplink signal(deltaMCS-Enabled). In addition, f_(c) is determined fromaccumulation-enabled, which is a parameter related to uplink powercontrol, and a TPC command included in the uplink grant.

The terminal 102 determines the PUCCH uplink transmit power in thesubframe i using formula (3).

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack} & \; \\{{P_{PUCCH}(i)} = \begin{Bmatrix}{{P_{{CMAX},c}(i)},} \\\begin{matrix}{P_{0{\_ PUCCH}} + {PL}_{c} + {h\left( {n_{CQI},{n_{{HARQ},}n_{SR}}} \right)} +} \\{{\Delta_{F\_ PUCCH}(F)} + {\Delta_{TxD}\left( F^{\prime} \right)} + {g(i)}}\end{matrix}\end{Bmatrix}} & (3)\end{matrix}$

P_(O_PUCCH) denotes the nominal power of the PUCCH. P_(O_PUCCH) isdetermined from P_(O_NOMINAL_PUCCH) and P_(O_UE_PUCCH).P_(O_NOMINAL_PUCCH) is a cell-specific parameter related to uplink powercontrol. P_(O_UE_PUCCH) is a UE-specific parameter related to uplinkpower control. n_(CQI) denotes the number of bits of the CQI, n_(HARQ)denotes the number of bits of the HARQ, and n_(SR) denotes the number ofbits of the SR. h(n_(CQI), n_(HARQ), n_(SR)) is a parameter defined tobe dependent on the respective numbers of bits, that is, PUCCH format.Δ_(F_PUCCH) is a parameter notified by the higher layer(deltaFList-PUCCH). ΔT×D is a parameter notified by the higher layer ina case where transmit diversity is configured. g is a parameter used toadjust PUCCH power control.

The terminal 102 determines the SRS uplink transmit power using formula(4).

[Math. 4]

P _(SRS,c)(i)=min{P _(CMAX,c)(i),P _(SRS_OFFSET,c)(m)+10 log₁₀(M_(SRS,c))+P _(O_PUSCH,c)(j)+α_(c)(j)·PL _(c)+∫_(c)(i)}   (4)

P_(SRS_OFFSET) is an offset for adjusting the SRS transmit power, and isincluded in the uplink power control parameters (uplink power controlrelated UE-specific parameter configuration). M_(SRS,c) denotes thebandwidth (the number of resource blocks in the frequency domain) of theSRS arranged in the serving cell c.

FIG. 22 is a diagram illustrating an example of information elementsincluded in the (first) uplink power control related parameterconfiguration (UplinkPowerControl). The uplink power control relatedparameter configuration includes a cell-specific configuration (uplinkpower control related cell-specific parameter configuration(UplinkPowerControlCommon)) and a dedicated configuration (uplink powercontrol related UE-specific parameter configuration(UplinkPowerControlDedicated)), and each configuration includesparameters related to uplink power control (information elements)configured to be cell-specific or UE-specific. The cell-specificconfiguration includes nominal PUSCH power (p0-NominalPUSCH), which iscell-specific configurable PUSCH power, an attenuation coefficient(channel loss compensation coefficient) α (alpha) for fractionaltransmit power control, nominal PUCCH power (p0-NominalPUCCH), which iscell-specific configurable PUCCH power, Δ_(F_PUCCH) (deltaFList-PUCCH)included in formula (3), and a power adjustment value(deltaPreambleMsg3) in a case where preamble message 3 is transmitted.

The UE-specific configuration includes UE-specific PUSCH power(p0-UE-PUSCH), which is UE-specific configurable PUSCH power, aparameter (deltaMCS-Enabled) related to the power adjustment value K_(s)based on the modulation and coding scheme, which is used in formula (2),a parameter (accumulationEnabled) required to configure a TPC command,UE-specific PUCCH power (p0-UE-PUCCH), which is UE-specific configurablePUCCH power, a power offset P_(SRS_OFFSET) of the periodic and aperiodicSRS (pSRS-Offset, pSRS-OffsetAp-r10), and a filter coefficient(filterCoefficient) of the reference signal received power RSRP. Theseconfigurations are configurable for the primary cell, and may be alsoconfigurable for the secondary cell in a similar manner. The dedicatedconfiguration for the secondary cell further includes a parameter(pathlossReference-r10) specifying the computation of a path loss usinga path loss measurement reference signal of the primary cell orsecondary cell (for example, a cell-specific reference signal).

FIG. 23 illustrates an example of information including an uplink powercontrol related parameter configurations (first uplink power controlrelated parameter configuration). A (first) uplink power control relatedcell-specific parameter configuration (UplinkPowerControlCommon1) isincluded in a common radio resource configuration(RadioResourceConfigCommon). A (first) uplink power control relatedUE-specific parameter configuration (UplinkPowerControlDedicated1) isincluded in a dedicated physical configuration(PhysicalConfigDedicated). A (first) uplink power control relatedcell-specific parameter configuration(UplinkPowerControlCommonSCell-r10-1) is included in a common radioresource configuration for the secondary cell(RadioResourceConfigCommonSCell-r10). A (first) uplink power controlrelated UE-specific parameter configuration for the secondary cell(UplinkPowerControlDedicatedSCell-r10-1) is included in a dedicatedphysical configuration for the secondary cell(PhysicalConfigDedicatedSCell-r10).

A dedicated physical configuration (for the primary cell) is included ina dedicated radio resource configuration (for the primary cell)(RadioResourceConfigDedicated). A dedicated physical configuration forthe secondary cell is included in a dedicated radio resourceconfiguration for the secondary cell(RadioResourceConfigDedicatedSCell-r10).The common radio resourceconfiguration and the dedicated radio resource configuration, describedabove, may be included in the RRC connection reconfiguration(RRCConnectionReconfiguration) or RRC re-establishment(RRCConnectionReestablishment) described in the second exemplaryembodiment. The common radio resource configuration for the secondarycell and the dedicated radio resource configuration for the secondarycell, described above, may be included in the SCelladdition/modification list described in the second exemplary embodiment.The common radio resource configuration and the dedicated radio resourceconfiguration, described above, may be configured for each terminalusing RRC signals (Dedicated signaling). The RRC connectionreconfiguration and the RRC re-establishment may be configured for eachterminal using RRC messages. The uplink power control relatedcell-specific parameter configuration described above may be configuredin the terminal 102 using system information. The uplink power controlrelated UE-specific parameter configuration described above may beconfigured for each terminal 102 using RRC signals (Dedicatedsignaling).

In the third embodiment, the terminal 102 can compute the uplinktransmit power (P_(PUSCH1), P_(PUCCH1), P_(SRS1)) of a variety of uplinksignals (PUSCH, PUCCH, SRS) on the basis of the first measurement targetconfiguration and second measurement target configuration described inthe first embodiment and second embodiment. The variety of uplinksignals may also be a plurality of types of uplink physical channels.The variety of uplink physical channels include at least one uplinkphysical channel among the pieces of control information (CQI, PMI, RI,Ack/Nack) included in PUSCH, PUCCH, UL DMRS, SRS, PRACH, and PUCCH.

In the third embodiment, the base station 101 notifies the terminal 102of the first measurement target configuration, the second measurementtarget configuration, and the uplink power control related parameterconfiguration. In an example, the terminal 102 computes a path loss(first path loss) in accordance with the notified information on thebasis of the first measurement target configuration and the uplink powercontrol related parameter configuration, and computes a first uplinktransmit power on the basis of the first path loss and the uplink powercontrol related parameter configuration. The terminal 102 also computesa path loss (second path loss) on the basis of the second measurementtarget configuration and the uplink power control related parameterconfiguration, and computes a second uplink transmit power on the basisof the second path loss and the uplink power control related parameterconfiguration.

That is, the first uplink transmit power may always be computed on thebasis of the measurement target notified using the first measurementtarget configuration, and the second uplink transmit power may always becomputed on the basis of the measurement target notified using thesecond measurement target configuration. More specifically, the firstuplink transmit power may always be computed on the basis of antennaport 0 for the cell-specific reference signal as the measurement targetnotified using the first measurement target configuration, and thesecond uplink transmit power may always be computed on the basis of aspecified resource (or antenna port) of the channel-state informationreference signal as the measurement target notified using the secondmeasurement target configuration. In another example, in a case where aplurality of measurement targets (for example, a plurality of specifiedresources or antenna ports for the channel-state information referencesignal) are specified in the second measurement target configuration,notification as to whether to compute the second uplink transmit powerusing one of the measurement targets may be given. In this case, a pathloss reference resource, which will be described below with reference toFIG. 24, may be configured in the first uplink power control relatedcell-specific parameter configuration, the first uplink power controlrelated cell-specific parameter configuration for the secondary cell,the first uplink power control related UE-specific parameterconfiguration, or the first uplink power control related UE-specificparameter configuration for the secondary cell illustrated in FIG. 22.In another example, the first uplink transmit power may always becomputed on the basis of antenna port 0 (or antenna ports 0 and 1) forthe cell-specific reference signal regardless of the first measurementtarget configuration. Furthermore, the terminal 102 may perform controlto determine whether to transmit an uplink signal at the first uplinktransmit power described above or to transmit an uplink signal at thesecond uplink transmit power described above, in accordance with thefrequency resource or the timing in which the uplink grant has beendetected.

In this manner, the first uplink transmit power and second uplinktransmit power may be fixedly associated with the first measurementobject configuration and second measurement target configuration (andthe measurement targets specified in the measurement targetconfigurations).

In a more specific example, in a case where carrier aggregation, whichallows communication using a plurality of carrier components (here, twocarrier components), is possible, the first measurement objectconfiguration or second measurement target configuration may beassociated with a carrier component. That is, the first measurementtarget configuration may be associated with the first carrier component,and the second measurement target configuration may be associated withthe second carrier component. In a case where the first carriercomponent is configured for the primary cell and the second carriercomponent is configured for the secondary cell, the first measurementtarget configuration may be associated with the primary cell and thesecond measurement target configuration may be associated with thesecondary cell.

That is, the base station 101 may configure the first measurement objectconfiguration and second measurement target configuration on acell-by-cell basis. In a case where the uplink grant has been detectedfrom the primary cell, the terminal 102 computes a first path loss and afirst uplink transmit power from the first measurement targetconfiguration, the uplink power control related cell-specific parameterconfiguration for the primary cell, and the uplink power control relatedUE-specific parameter configuration for the primary cell. In a casewhere the uplink grant has been detected from the secondary cell, theterminal 102 computes a second path loss and a second uplink transmitpower from the second measurement target configuration, the uplink powercontrol related cell-specific parameter configuration for the secondarycell, and the uplink power control related UE-specific parameterconfiguration for the secondary cell.

In another aspect, for example, if a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B, dynamicuplink signal transmission control for the terminal A is performed onlyin the primary cell, and dynamic uplink signal transmission control forthe terminal B is performed only in the secondary cell. Morespecifically, in order to cause the terminal 102 to transmit an uplinksignal to the base station 101, the base station 101 notifies theterminal 102 of an uplink grant that is included in the primary cell. Inorder to cause the terminal 102 to transmit an uplink signal to the RRH103, the base station 101 notifies the terminal 102 of an uplink grantthat is included in the secondary cell. In addition, the base station101 can utilize a TPC command, which is a correction value for uplinksignal transmit power control included in the uplink grant, to performuplink signal transmit power control for the base station 101 or the RRH103. The base station 101 configures a TPC command value included in theuplink grant so as to be suitable for the base station 101 or the RRH103 in accordance with the cell (carrier component, component carrier)in which the base station 101 notifies the terminal 102 of the uplinkgrant.

More specifically, in order to increase the uplink transmit power forthe base station 101, the base station 101 sets the power correctionvalue of the TPC command in the primary cell to be high. In order todecrease the uplink transmit power for the RRH 103, the base station 101sets the power correction value of the TPC command in the secondary cellto be low. The base station 101 performs uplink signal transmission anduplink transmit power control for the terminal A using the primary cell,and performs uplink signal transmission and uplink transmit powercontrol for the terminal B using the secondary cell.

By way of example, a downlink subframe is considered to be divided intoa first subset and a second subset. If an uplink grant is received insubframe n (n is a natural number), the terminal 102 transmits an uplinksignal in subframe n+4. Accordingly, an uplink subframe is naturallyconsidered to be divided into a first subset and a second subset. Forexample, if downlink subframes 0 and 5 are included in the first subsetand downlink subframes 1, 2, 3, 4, 6, 7, 8, and 9 are included in thesecond subset, naturally, uplink subframes 4 and 9 are included in thefirst subset and uplink subframes 1, 2, 3, 5, 6, 7, and 8 are includedin the second subset. In this case, if the first subset includes thedownlink subframe index in which the uplink grant has been detected, theterminal 102 computes a first path loss and a first uplink transmitpower on the basis of the first measurement target configuration and theuplink power control related parameter configuration. If the secondsubset includes the downlink subframe index in which the uplink granthas been detected, the terminal 102 computes a second path loss and asecond uplink transmit power on the basis of the second measurementtarget configuration and the uplink power control related parameterconfiguration. That is, the terminal 102 can perform control todetermine whether to transmit an uplink signal at the first uplinktransmit power or to transmit an uplink signal at the second uplinktransmit power in accordance with whether the first subset or the secondsubset includes the downlink subframe in which the uplink grant has beendetected.

The first subset may be composed of downlink subframes including a P-BCH(Physical Broadcast Channel), a PSS (Primary Synchronization Signal),and an SSS (Secondary Synchronization Signal). The second subset may becomposed of subframes not including a P-BCH, a PSS, or an SSS.

In another aspect, for example, if a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B, dynamicuplink signal transmission control for the terminal A is performed onlyin the first subframe subset, and dynamic uplink signal transmissioncontrol for the terminal B is performed only in the second subframesubset. More specifically, in order to cause the terminal 102 totransmit an uplink signal to the base station 101, the base station 101notifies the terminal 102 of an uplink grant that is included in thefirst subframe subset. In order to cause the terminal 102 to transmit anuplink signal to the RRH 103, the base station 101 notifies the terminal102 of an uplink grant that is included in the second subframe subset.In addition, the base station 101 can utilize a TPC command, which is acorrection value for uplink signal transmit power control included inthe uplink grant, to perform uplink signal transmit power control forthe base station 101 or the RRH 103. The base station 101 configures aTPC command value included in the uplink grant so as to be suitable forthe base station 101 or the RRH 103 in accordance with the subframesubset in which the base station 101 notifies the terminal 102 of theuplink grant. More specifically, in order to increase the uplinktransmit power for the base station 101, the base station 101 sets thepower correction value of the TPC command in the first subframe subsetto be high.

In order to decrease the uplink transmit power for the RRH 103, the basestation 101 sets the power correction value of the TPC command in thesecond subframe subset to be low. The base station 101 performs uplinksignal transmission and uplink transmit power control for the terminal Ausing the first subframe subset, and performs uplink signal transmissionand uplink transmit power control for the terminal B using the secondsubframe subset.

By way of example, in a case where the uplink grant has been detected inthe first control channel region, the terminal 102 computes a first pathloss and a first uplink transmit power on the basis of the firstmeasurement target configuration and the uplink power control relatedparameter configuration. In a case where the uplink grant has beendetected in the second control channel region, the terminal 102 computesa second path loss and a second uplink transmit power on the basis ofthe second measurement target configuration and the uplink power controlrelated parameter configuration. That is, the terminal 102 can performcontrol to determine whether to transmit an uplink signal at the firstuplink transmit power or to transmit an uplink signal at the seconduplink transmit power in accordance with the control channel region inwhich the uplink grant has been detected.

In another aspect, for example, if a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B, dynamicuplink signal transmission control for the terminal A is performed onlyin the first control channel (PDCCH) region, and dynamic uplink signaltransmission control for the terminal B is performed only in the secondcontrol channel (X-PDCCH) region. More specifically, in order to causethe terminal 102 to transmit an uplink signal to the base station 101,the base station 101 notifies the terminal 102 of an uplink grant thatis included in the first control channel region. In order to cause theterminal 102 to transmit an uplink signal to the RRH 103, the basestation 101 notifies the terminal 102 of an uplink grant that isincluded in the second control channel region. In addition, the basestation 101 can utilize a TPC command, which is a correction value foruplink signal transmit power control included in the uplink grant, toperform uplink signal transmit power control for the base station 101 orthe RRH 103.

The base station 101 configures a TPC command value included in theuplink grant so as to be suitable for the base station 101 or the RRH103 in accordance with the control channel region in which the basestation 101 notifies the terminal 102 of the uplink grant. Morespecifically, in order to increase the uplink transmit power for thebase station 101, the base station 101 sets the power correction valueof the TPC command in the first control channel region to be high. Inorder to decrease the uplink transmit power for the RRH 103, the basestation 101 sets the power correction value of the TPC command in thesecond control channel region to be low. The base station 101 performsuplink signal transmission and uplink transmit power control for theterminal A using the first control channel region, and performs uplinksignal transmission and uplink transmit power control for the terminal Busing the second control channel.

In the third embodiment, furthermore, the base station 101 notifies theterminal 102 of a radio resource control signal including the firstmeasurement object configuration and second measurement targetconfiguration, and notifies the terminal 102 of a radio resource controlsignal including the uplink power control related parameterconfiguration. The terminal 102 computes a first path loss and a firstuplink transmit power on the basis of the first measurement targetincluded in the first measurement target configuration and the uplinkpower control related parameter configuration, and computes a secondpath loss and a second uplink transmit power on the basis of the secondmeasurement target included in the second measurement targetconfiguration and the uplink power control related parameterconfiguration. The terminal 102 transmits an uplink signal to the basestation 101 at the first uplink transmit power or second uplink transmitpower.

Now referring to FIG. 1, it is assumed that the base station 101 and theRRH 103 are carrying out carrier aggregation, and are performingcommunication using two carrier components (Carrier Component, CC, Cell,cell) having different center frequencies for uplink and downlink. Thesecarrier components are called a first carrier component and a secondcarrier component, and the base station 101 and the RRH 103 are assumedto be capable of individual communication and coordinated communicationby using these carrier components. It is also assumed that the firstcarrier component is used for communication between the base station 101and the terminal 102 and the second carrier component is used forcommunication between the RRH 103 and the terminal 102. That is, thedownlink 105 or the uplink 106 is connected using the first carriercomponent, and the downlink 107 or the uplink 108 is connected using thesecond carrier component.

In this case, in a case where the uplink grant has been detected fromthe downlink 105 via the first carrier component, the terminal 102 canperform transmission to the uplink 106 at the first uplink transmitpower using the first carrier component. In a case where the uplinkgrant has been detected from the downlink 107 via the second carriercomponent, the terminal 102 can perform transmission to the uplink 108at the second uplink transmit power using the second carrier component.If the detected uplink grant includes a carrier indicator, the terminal102 may calculate a path loss and an uplink transmit power using a pathloss reference resource associated with the carrier (cell, primary cell,secondary cell, serving cell index) indicated by the carrier indicator.

Furthermore, the base station 101 schedules different carrier componentsfor a terminal 102 that communicates with the base station 101 and aterminal 102 that communicates with the RRH 103, and configures thefirst measurement object configuration or second measurement targetconfiguration for each of the carrier components. Accordingly, the basestation 101 can implement control to perform appropriate uplink transmitpower control for the terminal 102.

Now referring to FIG. 1, an uplink subframe subset in which the terminal102 transmits an uplink signal to the base station 101, and an uplinksubframe subset in which the terminal 102 transmits an uplink signal tothe RRH 103 are configured. That is, the terminal 102 is controlled totransmit an uplink signal to the base station 101 at timing differentfrom that at which the terminal 102 transmits an uplink signal to theRRH 103 so as to avoid the uplink signal transmitted from the terminal102 from causing interference to reception at other terminals 102. It isassumed that the subframe subset in which an uplink signal istransmitted to the base station 101 is represented by a first subset andthat the subframe subset in which an uplink signal is transmitted to theRRH 103 is represented by a second subset. In this case, the terminal102 implements transmission in the uplink 106 using the first subset,and transmission in the uplink 108 using the second subset. In order totransmit an uplink signal using the first subset, the terminal 102computes a first path loss and a first uplink transmit power using thefirst measurement target configuration and the uplink power controlrelated parameter configuration. In order to transmit an uplink signalusing the second subset, the terminal 102 computes a second path lossand computes a second uplink transmit power using the second measurementtarget configuration and the uplink power control related parameterconfiguration.

In addition, the base station 101 makes the timing (subframe subset) ofcommunication between the base station 101 and the terminal 102different from the timing (subframe subset) of communication between theRRH 103 and the terminal 102, and performs appropriate transmit powercontrol for the respective subsets. Accordingly, the base station 101can configure an appropriate uplink transmit power for the uplink 106 orthe uplink 108 in the terminal 102.

Now referring to FIG. 1, the terminal 102 can determine the timing atwhich the terminal 102 performs transmission using the uplink 106 or theuplink 108 in response to the detection of the uplink grant, inaccordance with whether the control channel region in which the uplinkgrant has been detected is the first control channel region or thesecond control channel region. That is, in a case where the uplink granthas been detected in the first control channel region of subframe n, theterminal 102 can transmit an uplink signal to the base station 101 insubframe n+4 at the first uplink transmit power. In a case where theuplink grant has been detected in the second control channel region ofsubframe n+1, the terminal 102 can transmit an uplink signal to the RRH103 in subframe n+5 at the second uplink transmit power.

In a case where the uplink grant has been detected in the first controlchannel region, the terminal 102 can transmit an uplink signal to theuplink 106 at the first uplink transmit power. If the uplink grant hasbeen detected in the second control channel region, the terminal 102 cantransmit an uplink signal to the uplink 108 at the second uplinktransmit power.

In addition, the base station 101 appropriately schedules the uplinkgrant in the first control channel region and the second control channelregion on the downlinks 105 and 107. Accordingly, the base station 101can configure an appropriate uplink transmit power for the uplink 106 orthe uplink 108 in the terminal 102.

In this manner, the terminal 102 can separate uplink transmission to thebase station 101 and uplink transmission to the RRH 103 in accordancewith the frequency resource or timing in which the uplink grant isdetected. Accordingly, even if terminals having greatly different uplinktransmit powers are configured, the terminals 102 can be controlled notto interfere with each other.

Exemplary Modification 1 of Third Embodiment

Next, Exemplary Modification 1 of the third embodiment will bedescribed. In Exemplary Modification 1 of the third embodiment, the basestation 101 can specify a reference signal (for example, thecell-specific reference signal or the channel-state informationreference signal) to be used for the computation of a path loss and aresource (or antenna port) as the measurement target using the uplinkpower control related parameter configuration. The reference signal tobe used for the computation of a path loss may be indicated by the firstmeasurement object configuration or second measurement targetconfiguration described in the first embodiment or the secondembodiment. The following description will be made of the details of amethod for configuring the reference signal to be used for thecomputation of a path loss and the resource as the measurement target.

It is assumed that the base station 101 and the RRH 103 are carrying outcarrier aggregation, and are performing communication using two carriercomponents (Carrier Component, CC, Cell, cell) having different centerfrequencies for uplink and downlink. These carrier components are calleda first carrier component and a second carrier component, and the basestation 101 and the RRH 103 are assumed to be capable of individualcommunication and coordinated communication by using these carriercomponents. The base station 101 may configure the first carriercomponent as the primary cell and configure the second carrier componentas the secondary cell. The base station 101 may specify, for the primarycell and the secondary cell, the resource of the reference signal to beused for the computation of a path loss using a path loss referenceresource such as an index.

The term path loss reference resource, as used herein, refers to aninformation element specifying the reference signal to be used (referredto) for the computation of a path loss and specifying the resource (orantenna port) as the measurement target, and refers to a measurementtarget configured in the first measurement target configuration orsecond measurement target configuration described in the firstembodiment or the second embodiment. Accordingly, the base station 101may associate the path loss to be used for the calculation of the uplinktransmit power with the measurement target (the reference signal and theantenna port index or measurement index) to be used for the computationof the path loss, by using the path loss reference resource.Alternatively, the path loss reference resource may be antenna portindex 0 for the cell-specific reference signal or the CSI-RS antennaport (or CSI-RS measurement index) for the channel-state informationreference signal described in the first embodiment or the secondembodiment. More specifically, if the index specified by the path lossreference resource is 0, the path loss reference resource representsantenna port index 0 for the cell-specific reference signal. If theindex is any other value, the path loss reference resource may beassociated with the CSI-RS measurement index for the channel-stateinformation reference signal or with the CSI-RS antenna port index. Inaddition, the path loss reference resource described above may beassociated with the pathlossReference described with reference to FIG.22.

More specifically, in a case where the second carrier component (SCell,secondary cell) is specified by the pathlossReference and the CSI-RSmeasurement index 1 for the channel-state information reference signalis specified by the path loss reference resource, a path loss may becomputed on the basis of the resource corresponding to the CSI-RSmeasurement index 1 included in the second carrier component, and theuplink transmit power may be calculated. In another example, if thefirst carrier component (PCell, primary cell) is specified by thepathlossReference and the CSI-RS measurement index 1 for thechannel-state information reference signal is specified by the path lossreference resource, a path loss may be computed on the basis of theresource corresponding to the CSI-RS measurement index 1 included in thefirst carrier component, and the uplink transmit power may becalculated. In addition, in a case where the detected uplink grantincludes a carrier indicator, the terminal 102 may calculate a path lossand an uplink transmit power using the path loss reference resourceassociated with the carrier (cell, primary cell, secondary cell, servingcell index) indicated by the carrier indicator.

In accordance with the foregoing procedure, the terminal 102 can computea path loss on the basis of the content of the path loss referenceresource notified by the base station 101, and can compute the uplinktransmit power on the basis of the path loss and the uplink powercontrol related parameter configuration.

FIG. 24 is a diagram illustrating the details of the path loss referenceresource. The path loss reference resource is an information element tobe added to the uplink power control related UE-specific parameterconfiguration (for the primary cell) and the uplink power controlrelated UE-specific parameter configuration for the secondary cell. Inthe path loss reference resource, a downlink reference signal(measurement target) to be used for the measurement of a path loss,which is configured in the measurement target configuration, isspecified. The base station 101 can specify the measurement targetspecified in the measurement target configuration, described in thefirst embodiment or second embodiment, for the terminal 102 using thepath loss reference resource. More specifically, the base station 101can select a measurement resource for use in path loss measurement forthe primary cell (first carrier component, PCell) and the secondary cell(second carrier component, SCell), from the measurement targetconfigured in the measurement target configuration. The terminal 102 cancompute a path loss for computing the uplink transmit power in theprimary cell and the secondary cell in accordance with the instructions,and can compute the uplink transmit power for the primary cell or thesecondary cell on the basis of the path loss and the uplink powercontrol related parameter configuration.

In another aspect, for example, if a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B, dynamicuplink signal transmission control for the terminal A is performed onlyin the primary cell, and dynamic uplink signal transmission control forthe terminal B is performed only in the secondary cell. Morespecifically, in order to cause the terminal 102 to transmit an uplinksignal to the base station 101, the base station 101 notifies theterminal 102 of an uplink grant that is included in the primary cell. Inorder to cause the terminal 102 to transmit an uplink signal to the RRH103, the base station 101 notifies the terminal 102 of an uplink grantthat is included in the secondary cell. In addition, the base station101 can utilize information concerning a TPC command, which is acorrection value for uplink signal transmit power control included inthe uplink grant, to perform uplink signal transmit power control forthe base station 101 or the RRH 103. The base station 101 configures aTPC command value included in the uplink grant so as to be suitable forthe base station 101 or the RRH 103 in accordance with the cell (carriercomponent, component carrier) in which the base station 101 notifies theterminal 102 of the uplink grant. More specifically, in order toincrease the uplink transmit power for the base station 101, the basestation 101 sets the power correction value of the TPC command in theprimary cell to be high. In order to decrease the uplink transmit powerfor the RRH 103, the base station 101 sets the power correction value ofthe TPC command in the secondary cell to be low. The base station 101performs uplink signal transmission and uplink transmit power controlfor the terminal A using the primary cell, and performs uplink signaltransmission and uplink transmit power control for the terminal B usingthe secondary cell.

FIG. 25 is a diagram illustrating the details of the path loss referenceresource based on the timing at which the terminal 102 detected theuplink grant. The base station 101 can configure two or more path lossreference resources (a first path loss reference resource and a secondpath loss reference resource) for the terminal 102. The second path lossreference resource is a parameter that can be added at any time using anaddition/modification list. The path loss reference resource isassociated with the measurement target configured in the measurementtarget configuration. For example, it is assumed that an uplink grantdetection subframe subset (uplink grant detection pattern) is configuredin the measurement target and that an uplink grant has been detected inthe downlink subframe included in the uplink grant detection pattern. Inthis case, the terminal 102 computes a path loss using the measurementtarget associated with the uplink grant detection subframe subset, andcomputes the uplink transmit power on the basis of the path loss.Specifically, in a case where a plurality of path loss referenceresources (a first path loss reference resource and a second path lossreference resource) are configured, the terminal 102 associates theuplink grant detection subframe subset with the path loss referenceresources.

More specifically, the first path loss reference resource is associatedwith the first subframe subset. Also, the second path loss referenceresource is associated with the second subframe subset. In addition, theterminal 102 selects a measurement target configuration on which thecomputation of the uplink transmit power is based from the path lossreference resources, and computes the uplink transmit power on the basisof the path loss computed based on the received signal power of themeasurement target specified in the measurement target configuration. Inan example, the first path loss reference resource may specify the firstmeasurement target configuration, that is, antenna port 0 for thecell-specific reference signal, and may be transmitted from the basestation 101. The second path loss reference resource may specify thesecond measurement target configuration, that is, antenna port 15 forthe channel-state information reference signal, and may be transmittedfrom the RRH 103. Accordingly, different measurement targets arereferred to in accordance with the subframe in which the uplink grant isdetected. As a result, in a case where an uplink signal has beendetected in the first subframe subset, the transmit power suitable forthe base station 101 is configured. In a case where an uplink signal hasbeen detected in the second subframe subset, the transmit power suitablefor the RRH 103 is configured. Accordingly, appropriate uplink transmitpower control can be performed while the measurement target to be usedfor the path loss computation is switched at the timing at which theuplink grant is detected.

The second path loss reference resource is a path loss referenceresource that can be added from a path loss reference resourceaddition/modification list. That is, the base station 101 may define aplurality of path loss reference resources for one cell (for example,the primary cell). The base station 101 may instruct the terminal 102 tosimultaneously compute path losses for a plurality of path lossreference resources. The base station 101 may add the second path lossreference resource by configuring the path loss reference resource IDand the measurement target using the path loss reference resourceaddition/modification list, so that the second path loss referenceresource can be added at any time. If it is no longer necessary tocompute path losses for a plurality of path loss reference resources,the base station 101 may remove an unnecessary path loss referenceresource using a path loss reference resource removal list. An exampleof the method for computing the second path loss in this case will nowbe given. The second path loss reference resource may specify aplurality of first measurement object configurations or a plurality ofsecond measurement target configurations, that is, for example, antennaports 15 and 16 for the channel-state information reference signal,etc., in the path loss reference resource addition/modification list.

In this case, a second path loss may be computed on the basis of thereceived signal power at antenna ports 15 and 16 for the channel-stateinformation reference signal. In this case, the path loss calculatedfrom antenna port 15 and the path loss calculated from antenna port 16may be averaged to determine a second path loss, or the larger orsmaller one of the two path loss values may be used as a second pathloss. Alternatively, the two path losses may be subjected to linearprocessing to obtain a second path loss. The path losses described abovemay be calculated from antenna port 0 for the cell-specific referencesignal and antenna port 15 for the channel-state information referencesignal. In another example, the second path loss reference resource mayspecify a plurality of second measurement target configurations, thatis, antenna ports 15 and 16 for the channel-state information referencesignal, etc., in the path loss reference resource addition/modificationlist. In this case, a second path loss and a third path loss may becomputed on the basis of the received signal power at antenna ports 15and 16 for the channel-state information reference signal. In this case,the first path loss, the second path loss, and the third path loss maybe associated with the first subframe subset, the second subframesubset, and the third subframe subset, respectively.

The measurement target included in the first path loss referenceresource and second path loss reference resource may be antenna port 0for the cell-specific reference signal or the CSI-RS antenna port index(CSI-RS measurement index) described in the first embodiment or thesecond embodiment.

The measurement target may include an uplink grant detection pattern.The uplink grant detection pattern may be implemented using ameasurement subframe pattern (MeasSubframePattern-r10) included in themeasurement object EUTRA in the measurement object in FIG. 14.

In the foregoing, the measurement target is associated with the uplinkgrant detection pattern. In another example, the measurement target mayinclude no uplink grant detection pattern, and the measurement targetmay be associated with the transmission timing of the measurementreport. Specifically, the terminal 102 may associate the measurementresult of the measurement target with the subframe pattern that theterminal 102 notifies the base station 101 of. In a case where an uplinkgrant has been detected in the downlink subframe associated with thesubframe pattern, the terminal 102 can compute a path loss using themeasurement target, and can compute the uplink transmit power.

While a description has been given here of the addition to the uplinkpower control related UE-specific parameter configuration for theprimary cell, a similar configuration may be added for the secondarycell. For the secondary cell, however, since a path loss reference(pathlossReference-r10) is configured, a path loss is computed based onthe reference signal included in either the primary cell or thesecondary cell. Specifically, if the primary cell is selected, a pathloss is computed based on the path loss reference resource in the uplinkpower control related UE-specific parameter configuration for theprimary cell. If the secondary cell is selected, a path loss is computedbased on the path loss reference resource in the uplink power controlrelated UE-specific parameter configuration for the secondary cell. Inaddition, the path loss reference resource described above may beassociated with the path loss reference (pathlossReference-r10). Morespecifically, if the second carrier component (SCell, secondary cell) isspecified in the path loss reference (pathlossReference-r10) and if theCSI-RS measurement index 1 for the channel-state information referencesignal is specified in the path loss reference resource, a path loss maybe computed on the basis of the resource corresponding to the CSI-RSmeasurement index 1 included in the second carrier component, and theuplink transmit power may be calculated. In another example, if thefirst carrier component (PCell, primary cell) is specified in the pathloss reference (pathlossReference-r10) and if CSI-RS measurement index 1for the channel-state information reference signal is specified in thepath loss reference resource, a path loss may be computed on the basisof the resource corresponding to the CSI-RS measurement index 1 includedin the first carrier component, and the uplink transmit power may becalculated.

In another aspect, for example, if a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B, dynamicuplink signal transmission control for the terminal A is performed onlyin the first subframe subset, and dynamic uplink signal transmissioncontrol for the terminal B is performed only in the second subframesubset. More specifically, in order to cause the terminal 102 totransmit an uplink signal to the base station 101, the base station 101notifies the terminal 102 of an uplink grant that is included in thefirst subframe subset. In order to cause the terminal 102 to transmit anuplink signal to the RRH 103, the base station 101 notifies the terminal102 of an uplink grant that is included in the second subframe subset.In addition, the base station 101 can utilize a TPC command, which is acorrection value for uplink signal transmit power control included inthe uplink grant, to perform uplink signal transmit power control forthe base station 101 or the RRH 103. The base station 101 configures aTPC command value included in the uplink grant so as to be suitable forthe base station 101 or the RRH 103 in accordance with the subframesubset in which the base station 101 notifies the terminal 102 of theuplink grant.

More specifically, in order to increase the uplink transmit power forthe base station 101, the base station 101 sets the power correctionvalue of the TPC command in the first subframe subset to be high. Inorder to decrease the uplink transmit power for the RRH 103, the basestation 101 sets the power correction value of the TPC command in thesecond subframe subset to be low. The base station 101 performs uplinksignal transmission and uplink transmit power control for the terminal Ausing the first subframe subset, and performs uplink signal transmissionand uplink transmit power control for the terminal B using the secondsubframe subset.

FIG. 26 is a diagram illustrating the details of the path loss referenceresource based on a control channel region in which the terminal 102detects the uplink grant. As in FIG. 25, the base station 101 mayconfigure two or more path loss reference resources (a first path lossreference resource and a second path loss reference resource) for theterminal 102. The second path loss reference resource is a parameterthat can be added at any time using an addition/modification list. Thepath loss reference resource is associated with the measurement targetconfigured in the measurement target configuration. For example, it isassumed that an uplink grant detection region (a first control channelregion and a second control channel region) is configured in themeasurement target and that an uplink grant has been detected in thedownlink control channel region included in the uplink grant detectionregion. In this case, the terminal 102 computes a path loss using themeasurement target associated with the uplink grant detection region,and computes the uplink transmit power on the basis of the path loss.Specifically, in a case where a plurality of path loss referenceresources (a first path loss reference resource and a second path lossreference resource) are configured, the terminal 102 associates theuplink grant detection region with the path loss reference resource.

More specifically, the first path loss reference resource is associatedwith the first control channel region. Also, the second path lossreference resource is associated with the second control channel region.In addition, the terminal 102 selects a measurement target configurationon which the computation of the uplink transmit power is based from thepath loss reference resources, and computes the uplink transmit power onthe basis of the path loss computed based on the received signal powerof the measurement target specified in the measurement targetconfiguration. Accordingly, the terminal 102 can transmit an uplinksignal at the uplink transmit power computed in accordance with themeasurement target using the region in which the uplink grant has beendetected. An example of a method for computing the second path loss in acase where a plurality of second measurement target configurations areassociated with the second path loss reference resource will further begiven. The second path loss reference resource may specify a pluralityof first measurement object configurations or a plurality of secondmeasurement target configurations, that is, for example, antenna ports15 and 16 for the channel-state information reference signal, etc., inthe path loss reference resource addition/modification list. In thiscase, a second path loss may be computed on the basis of the receivedsignal power at antenna ports 15 and 16 for the channel-stateinformation reference signal.

In this case, the path loss calculated from antenna port 15 and the pathloss calculated from antenna port 16 may be averaged to determine asecond path loss, or the larger or smaller one of the two path lossvalues may be selected as a second path loss. Alternatively, the twopath losses may be subjected to linear processing to obtain a secondpath loss. The path losses described above may be calculated fromantenna port 0 for the cell-specific reference signal and antenna port15 for the channel-state information reference signal. In anotherexample, the second path loss reference resource may specify a pluralityof second measurement target configurations, that is, antenna ports 15and 16 for the channel-state information reference signal, etc., in thepath loss reference resource addition/modification list. In this case, asecond path loss and a third path loss may be computed on the basis ofthe received signal power at antenna ports 15 and 16 for thechannel-state information reference signal. In this case, the first pathloss, the second path loss, and the third path loss may be associatedwith the first subframe subset, the second subframe subset, and thethird subframe subset, respectively.

The path loss measurement resource may be the cell-specific referencesignal antenna port 0 or the CSI-RS antenna port index (CSI-RSmeasurement index) described in the first embodiment or the secondembodiment.

In another aspect, for example, if a terminal that communicates with abase station is represented by terminal A and a terminal thatcommunicates with an RRH is represented by terminal B, dynamic uplinksignal transmission control for the terminal A is performed only in thefirst control channel (PDCCH) region, and dynamic uplink signaltransmission control for the terminal B is performed only in the secondcontrol channel (X-PDCCH) region. More specifically, in order to causethe terminal 102 to transmit an uplink signal to the base station 101,the base station 101 notifies the terminal 102 of an uplink grant thatis included in the first control channel region. In order to cause theterminal 102 to transmit an uplink signal to the RRH 103, the basestation 101 notifies the terminal 102 of a physical downlink controlchannel (uplink grant) that is included in the second control channelregion. In addition, the base station 101 can utilize a TPC command,which is a correction value for uplink signal transmit power controlincluded in the uplink grant, to perform uplink signal transmit powercontrol for the base station 101 or the RRH 103.

The base station 101 configures a TPC command value included in theuplink grant so as to be suitable for the base station 101 or the RRH103 in accordance with the control channel region in which the basestation 101 notifies the terminal 102 of the uplink grant. Morespecifically, in order to increase the uplink transmit power for thebase station 101, the base station 101 sets the power correction valueof the TPC command in the first control channel region to be high. Inorder to decrease the uplink transmit power for the RRH 103, the basestation 101 sets the power correction value of the TPC command in thesecond control channel region to be low. The base station 101 performsuplink signal transmission and uplink transmit power control for theterminal A using the first control channel region, and performs uplinksignal transmission and uplink transmit power control for the terminal Busing the second control channel.

In Exemplary Modification 1 of the third embodiment, the base station101 notifies the terminal 102 of a radio resource control signalincluding an uplink power control related parameter configuration inwhich a path loss reference resource is configured, and notifies theterminal 102 of an uplink grant. The terminal 102 computes a path lossand an uplink transmit power in accordance with the information includedin the radio resource control signal on the basis of the path lossreference resource and the uplink power control related parameterconfiguration, and transmits an uplink signal to the base station 101 atthe uplink transmit power.

In Exemplary Modification 1 of the third embodiment, furthermore, thebase station 101 notifies the terminal 102 of a radio resource controlsignal including an uplink power control related parameter configurationin which first path loss reference resource and second path lossreference resource are configured. Further, the terminal 102 computes afirst path loss on the basis of the first path loss reference resource,computes a second path loss on the basis of the second path lossreference resource, and computes the uplink transmit power on the basisof the first path loss or second path loss and the uplink power controlrelated parameter configuration.

In Exemplary Modification 1 of the third embodiment, furthermore, thebase station 101 notifies the terminal 102 of a radio resource controlsignal including an uplink power control related parameter configurationin which primary cell-specific and secondary cell-specific path lossreference resources are configured, and notifies the terminal 102 of anuplink grant. The terminal 102 receives a radio resource control signalincluding an uplink power control related parameter configuration inwhich primary cell-specific and secondary cell-specific path lossreference resources are configured. In a case where the uplink grant hasbeen detected in the primary cell, the terminal 102 computes a path lossand an uplink transmit power level on the basis of a path loss referenceresource included in the uplink power control related UE-specificparameter configuration for the primary cell and the uplink powercontrol related parameter configuration. In a case where the uplinkgrant has been detected in the secondary cell, the terminal 102 computesa path loss and an uplink transmit power level on the basis of a pathloss reference resource included in the uplink power control relatedUE-specific parameter configuration for the secondary cell and theuplink power control related parameter configuration. The terminal 102transmits an uplink signal to the base station 101 at the uplinktransmit power obtained by performing computation on the cell in whichthe uplink grant has been detected.

In Exemplary Modification 1 of the third embodiment, furthermore, thebase station 101 notifies the terminal 102 of a radio resource controlsignal including an uplink power control related parameter configurationin which first path loss reference resource and second path lossreference resource are configured, and notifies the terminal 102 of anuplink grant. In a case where the uplink grant has been detected in adownlink subframe included in a first subframe subset, the terminal 102computes, in accordance with information included in the radio resourcecontrol signal, a path loss and an uplink transmit power on the basis ofthe first path loss reference resource and the uplink power controlrelated parameter configuration. In a case where the uplink grant hasbeen detected in a downlink subframe included in a second subframesubset, the terminal 102 computes a path loss and an uplink transmitpower on the basis of the second path loss reference resource and theuplink power control related parameter configuration. The terminal 102transmits an uplink signal to the base station 101 at the uplinktransmit power in an uplink subframe included in the subframe subset.

In Exemplary Modification 1 of the third embodiment, furthermore, in acase where the uplink grant has been detected in a first control channelregion, the terminal 102 computes a first path loss and a first uplinktransmit power on the basis of the first path loss reference resourceand the uplink power control related parameter configuration. In a casewhere the uplink grant has been detected in a second control channelregion, the terminal 102 computes a second path loss and a second uplinktransmit power on the basis of the second path loss reference resourceand the uplink power control related parameter configuration. Theterminal 102 transmits an uplink signal to the base station 101 at thefirst uplink transmit power or second uplink transmit power inaccordance with the timing at which the uplink grant was detected.

Now referring to FIG. 1 in more detail, in a case where a plurality ofpath loss reference resources (a first path loss reference resource anda second path loss reference resource) are configured, the terminal 102associates the control channel region in which the uplink grant isdetected with the path loss reference resources. More specifically, thefirst path loss reference resource is associated with the first controlchannel region. Also, the second path loss reference resource isassociated with the second control channel region. In addition, theterminal 102 selects a measurement target configuration on which thecomputation of the uplink transmit power is based from the path lossreference resources, and computes the uplink transmit power on the basisof the path loss based on the received signal power of the measurementtarget specified in the measurement target configuration. In an example,the first path loss reference resource specifies the first measurementtarget configuration, that is, antenna port 0 for the cell-specificreference signal, and may be transmitted from the base station 101. Thesecond path loss reference resource specifies the second measurementtarget configuration, that is, antenna port 15 for the channel-stateinformation reference signal, and may be transmitted from the RRH 103.

Accordingly, different measurement targets are referred to in accordancewith the control channel region in which the uplink grant is detected.As a result, in a case where an uplink signal has been detected in thefirst control channel region, the transmit power suitable for the basestation 101 is configured. In a case where an uplink signal has beendetected in the second control channel region, the transmit powersuitable for the RRH 103 is configured. Accordingly, appropriate uplinktransmit power control can be performed while the measurement target tobe used for the path loss computation is switched in accordance with thecontrol channel region in which the uplink grant is detected. Inaddition, referring to different measurement targets in accordance withthe control channel region will eliminate the need for a base station tonotify the terminal 102 of the subframe pattern described above.

In another example, the base station 101 may reconfigure a variety ofuplink power control related parameter configurations for the terminal102 in order to perform appropriate uplink transmit power control for abase station or the RRH 103. In order to perform appropriate uplinktransmit power control for transmission to a base station or an RRH, asdescribed above, the base station 101 needs to switch between path lossmeasurement based on the first measurement target configuration and pathloss measurement based on the second measurement target configuration.However, in a case where the terminal 102 performs communication witheither a base station or an RRH on the order of several tens to severalhundreds of subframes and performs switching semi-statically, the basestation 101 can perform appropriate uplink transmit power control byupdating the measurement target configuration (first measurement targetconfiguration, second measurement target configuration) described aboveand the parameter configuration related to the path loss referenceresource described above. That is, it is possible to configureappropriate transmit power for the base station 101 or the RRH 103 byconfiguring only the first path loss reference resources illustrated inFIG. 25 or FIG. 26 and by performing appropriate configuration.

Exemplary Modification 2 of Third Embodiment

In Exemplary Modification 2 of the third embodiment, a plurality ofuplink power control related parameter configurations are configured,and the terminal 102 can compute the uplink transmit power of a varietyof uplink signals (PUSCH, PUCCH, SRS) (P_(PUSCH), P_(PUCCH), P_(SRS))using the respective uplink power control related parameterconfigurations.

In Exemplary Modification 2 of the third embodiment, the base station101 configures a plurality of uplink power control related parameterconfigurations (for example, a first uplink power control relatedparameter configuration and a second uplink power control relatedparameter configuration), and notifies the terminal 102 of the uplinkpower control related parameter configurations. The terminal 102computes a path loss in accordance with the notified information on thebasis of the first uplink power control related parameter configuration,and computes the uplink transmit power on the basis of the path loss andthe first uplink power control related parameter configuration. Theterminal 102 further computes a path loss on the basis of the seconduplink power control related parameter configuration, and computes theuplink transmit power on the basis of the path loss and the seconduplink power control related parameter configuration. Here, the uplinktransmit power computed based on the first uplink power control relatedparameter configuration is represented by a first uplink transmit power,and the uplink transmit power computed based on the second uplink powercontrol related parameter configuration is represented by a seconduplink transmit power.

The terminal 102 performs control to determine whether to transmit anuplink signal at the first uplink transmit power or to transmit anuplink signal at the second uplink transmit power in accordance with thefrequency resource and timing in which the uplink grant has beendetected.

The base station 101 may individually configure the information elementsincluded in each of the first uplink power control related parameterconfiguration and the second uplink power control related parameterconfiguration. A specific description will now be given with referenceto, for example, FIGS. 27 to 30. FIG. 27 is a diagram illustrating anexample of the second uplink power control related parameterconfiguration according to this embodiment of the claimed invention. Thesecond upper link power control related parameter configuration iscomposed of a second uplink power control related cell-specificparameter configuration-r11 (for the primary cell), a second uplinkpower control related cell-specific parameter configuration-r11 for thesecondary cell, a second uplink power control related UE-specificparameter configuration-r11 (for the primary cell), and a second uplinkpower control related UE-specific parameter configuration-r11 for thesecondary cell.

The first uplink power control related parameter configuration issimilar to that illustrated in FIGS. 22 and 24. In this embodiment ofthe claimed invention, a first uplink power control relatedcell-specific parameter configuration-r11 (for the primary cell), afirst uplink power control related cell-specific parameterconfiguration-r11 for the secondary cell, a first uplink power controlrelated UE-specific parameter configuration-r11 (for the primary cell),and a first uplink power control related UE-specific parameterconfiguration-r11 for the secondary cell may be included.

FIG. 28 is a diagram illustrating an example of the first uplink powercontrol related parameter configuration and the second uplink powercontrol related parameter configuration included in each radio resourceconfiguration. The common radio resource configuration (for the primarycell) includes a first uplink power control related cell-specificparameter configuration (for the primary cell) and a second uplink powercontrol related cell-specific parameter configuration-r11 (for theprimary cell). An uplink power control related cell-specific parameterconfiguration-r11 (for the primary cell) may also be included. Thecommon radio resource configuration for the secondary cell includes afirst uplink power control related cell-specific parameter configurationfor the secondary cell and a second uplink power control relatedcell-specific parameter configuration-r11 for the secondary cell. Anuplink power control related cell-specific parameter configuration-r11for the secondary cell may also be included. The dedicated physicalconfiguration (for the primary cell) includes a first uplink powercontrol related UE-specific parameter configuration (for the primarycell) and a second uplink power control related UE-specific parameterconfiguration-r11 (for the primary cell).

The dedicated physical configuration for the secondary cell includes afirst uplink power control related UE-specific parameter configurationfor the secondary cell and a second uplink power control relatedUE-specific parameter configuration-r11 for the secondary cell. Inaddition, the dedicated physical configuration (for the primary cell) isincluded in a dedicated radio resource configuration (for the primarycell) (RadioResourceConfigDedicated). In addition, the dedicatedphysical configuration for the secondary cell is included in a dedicatedradio resource configuration for the secondary cell(RadioResourceConfigDedicatedSCell-r10). The common radio resourceconfiguration and the dedicated radio resource configuration, describedabove, may be included in the RRC connection reconfiguration(RRCConnectionReconfiguration) or RRC re-establishment(RRCConnectionReestablishment) described in the second exemplaryembodiment. The common radio resource configuration for the secondarycell and the dedicated radio resource configuration for the secondarycell, described above, may be included in the SCelladdition/modification list described in the second exemplary embodiment.The common radio resource configuration and the dedicated radio resourceconfiguration, described above, may be configured for each terminal 102using RRC signals (Dedicated signaling). The RRC connectionreconfiguration and the RRC re-establishment may be configured for eachterminal using RRC messages.

FIG. 29 is a diagram illustrating an example of the second uplink powercontrol related cell-specific parameter configuration. The informationelements included in the second uplink power control relatedcell-specific parameter configuration-r11 (for the primary cell) or thesecond uplink power control related cell-specific parameterconfiguration-r11 for the secondary cell may be configured such that allthe information elements illustrated in FIG. 29 are included.Alternatively, the information elements included in the second uplinkpower control related cell-specific parameter configuration-r11 (for theprimary cell) or the second uplink power control related cell-specificparameter configuration-r11 for the secondary cell may be configuredsuch that at least one information element among the informationelements illustrated in FIG. 29 is included. Alternatively, none of theinformation elements included in the second uplink power control relatedcell-specific parameter configuration-r11 (for the primary cell) or thesecond uplink power control related cell-specific parameterconfiguration-r11 for the secondary cell may be included. In this case,the base station 101 selects a release, and notifies the terminal 102 ofinformation concerning the release. An information element that is notconfigured in the second uplink power control related cell-specificparameter configuration may be shared with the first uplink powercontrol related cell-specific parameter configuration.

FIG. 30 is a diagram illustrating an example of the first uplink powercontrol related UE-specific parameter configuration and the seconduplink power control related UE-specific parameter configuration. A pathloss reference resource is configured in the first uplink power controlrelated UE-specific parameter configuration for the primary cell and/orthe secondary cell. In addition to the information elements illustratedin FIG. 22, a path loss reference resource is configured in the seconduplink power control related UE-specific parameter configuration for theprimary cell and/or the secondary cell. The information elementsincluded in the second uplink power control related UE-specificparameter configuration-r11 (for the primary cell) or the second uplinkpower control related UE-specific parameter configuration-r11 for thesecondary cell may be configured such that all the information elementsillustrated in FIG. 30 are included.

Alternatively, the information elements included in the second uplinkpower control related UE-specific parameter configuration-r11 (for theprimary cell) or the second uplink power control related UE-specificparameter configuration-r11 for the secondary cell may be configuredsuch that only at least one information element among the informationelements illustrated in FIG. 30 is included. Alternatively, none of theinformation elements included in the second uplink power control relatedUE-specific parameter configuration-r11 (for the primary cell) or thesecond uplink power control related UE-specific parameterconfiguration-r11 for the secondary cell may be included. In this case,the base station 101 selects a release, and notifies the terminal 102 ofinformation concerning the release. An information element that is notconfigured in the second uplink power control related UE-specificparameter configuration may be shared with the first uplink powercontrol related UE-specific parameter configuration. Specifically, if apath loss reference resource is not configured in the second uplinkpower control related UE-specific parameter configuration, the path lossis computed based on the path loss reference resource configured in thefirst uplink power control related UE-specific parameter configuration.

The path loss reference resource may be the same as that illustrated inthe third embodiment (FIG. 24). That is, a measurement target specifyinga path loss reference resource may be associated with the indexassociated with cell-specific reference signal antenna port 0 or theCSI-RS antenna port index (CSI-RS measurement index) (FIG. 31).Alternatively, the path loss reference resource illustrated in FIG. 32or FIG. 33 may be used. FIG. 32 is a diagram illustrating an example ofthe path loss reference resource (example 1). A plurality of measurementtargets are configured in the path loss reference resource. The terminal102 can compute a path loss using at least one of these measurementtargets. FIG. 33 is a diagram illustrating another example of the pathloss reference resource (example 2). A measurement target to be added tothe path loss reference resource may be added using anaddition/modification list. The number of measurement targets to beadded may be determined by the maximum value of measurement target ID.The measurement target ID may be determined by a measurement object ID.In other words, the number of measurement targets to be added may be thesame as the number of measurement target configurations.

In addition, a measurement target that is no longer necessary may beremoved using a removal list. The foregoing may also apply to the thirdexemplary embodiment and Exemplary Modification 1 of the third exemplaryembodiment. An example of a method for computing a path loss in a casewhere a plurality of first measurement object configuration and secondmeasurement target configuration are associated with the path lossreference resource will now be given. The path loss reference resourcemay specify a plurality of first measurement object configuration andsecond measurement target configuration, that is, antenna ports 15 and16 for the channel-state information reference signal, etc., in the pathloss reference resource addition/modification list. In this case, asecond path loss may be computed on the basis of the received signalpower at antenna ports 15 and 16 for the channel-state informationreference signal. In this case, the path loss calculated from antennaport 15 and the path loss calculated from antenna port 16 may beaveraged to determine a second path loss, or the larger or smaller oneof the two path loss values may be used as a second path loss.Alternatively, the two path losses may be subjected to linear processingto obtain a second path loss. The path losses described above may becalculated from antenna port 0 for the cell-specific reference signaland antenna port 15 for the channel-state information reference signal.In another example, the second path loss reference resource may specifya plurality of second measurement target configurations, that is,antenna ports 15 and 16 for the channel-state information referencesignal, etc., in the path loss reference resource addition/modificationlist. In this case, a second path loss and a third path loss may becomputed on the basis of the received signal power at antenna ports 15and 16 for the channel-state information reference signal. In this case,the first path loss, the second path loss, and the third path loss maybe associated with the first subframe subset, the second subframesubset, and the third subframe subset, respectively.

By way of example, a downlink subframe is considered to be divided intoa first subset and a second subset. If an uplink grant is received insubframe n (n is a natural number), the terminal 102 transmits an uplinksignal in subframe n+4. Accordingly, an uplink subframe is naturallyconsidered to be divided into a first subset and a second subset. Thefirst subset may be associated with the first uplink power controlrelated parameter configuration, and the second subset may be associatedwith the second uplink power control related parameter configuration.Specifically, if the uplink grant has been detected in the downlinksubframe included in the first subset, the terminal 102 computes a pathloss on the basis of a variety of information elements included in thefirst uplink power control related parameter configuration and the pathloss reference resource (measurement target) included in the firstuplink power control related parameter configuration, and computes afirst uplink transmit power. If the uplink grant has been detected inthe downlink subframe included in the second subset, the terminal 102computes a path loss on the basis of a variety of information elementsincluded in the second uplink power control related parameterconfiguration and the path loss reference resource (measurement target)included in the second uplink power control related parameterconfiguration, and computes a second uplink transmit power.

By way of example, the control channel region including an uplink grantand the uplink power control related parameter configuration areassociated with each other. More specifically, the base station 101 canswitch the uplink power control related parameter configuration to beused for the computation of the uplink transmit power in accordance within which control channel region (a first control channel region and asecond control channel region) the terminal 102 has detected the uplinkgrant. Specifically, if the uplink grant has been detected in the firstcontrol channel region, the terminal 102 computes a path loss using thefirst uplink power control related parameter configuration, and computesthe uplink transmit power. If the uplink grant has been detected in thesecond control channel region, the terminal 102 computes a path lossusing the second uplink power control related parameter configuration,and computes the uplink transmit power.

In Exemplary Modification 2 of the third embodiment, the base station101 notifies the terminal 102 of the first uplink power control relatedparameter configuration and second uplink power control relatedparameter configuration. In an example, the terminal 102 computes a pathloss (first path loss) in accordance with the notified information onthe basis of the first uplink power control related parameterconfiguration, and computes a first uplink transmit power on the basisof the first path loss and the first uplink power control relatedparameter configuration. The terminal 102 also computes a path loss(second path loss) on the basis of the second uplink power controlrelated parameter configuration, and computes a second uplink transmitpower on the basis of the second path loss and the second uplink powercontrol related parameter configuration. That is, the first uplinktransmit power may always be computed based on the measurement targetnotified using the first uplink power control related parameterconfiguration. The second uplink transmit power may always be computedbased on the measurement target notified using the second uplink powercontrol related parameter configuration. In addition, the terminal 102may perform control to determine whether to transmit an uplink signal atthe first uplink transmit power described above or to transmit an uplinksignal at the second uplink transmit power described above, inaccordance with the frequency resource and timing in which the uplinkgrant has been detected.

In this manner, the first uplink transmit power and second uplinktransmit power may be fixedly associated with the first uplink powercontrol related parameter configuration and second uplink power controlrelated parameter configuration.

In Exemplary Modification 2 of the third embodiment, furthermore, thebase station 101 notifies the terminal 102 of a radio resource controlsignal including the first uplink power control related parameterconfiguration and second uplink power control related parameterconfiguration, and notifies the terminal 102 of an uplink grant. Theterminal 102 computes a first path loss and a first uplink transmitpower on the basis of the first uplink power control related parameterconfiguration, and computes a second path loss and a second uplinktransmit power on the basis of the second uplink power control relatedparameter configuration. If the uplink grant has been detected, theterminal 102 transmits an uplink signal at the first uplink transmitpower or second uplink transmit power.

The configuration of a plurality of uplink power control relatedparameter configurations allows the terminal 102 to select anappropriate uplink power control related parameter configuration for thebase station 101 or the RRH 103, and to transmit an uplink signal at anappropriate uplink transmit power to the base station 101 or the RRH103. More specifically, at least one type of information element amongthe information elements included in the first uplink power controlrelated parameter configuration and second uplink power control relatedparameter configuration may be configured as a different value. Forexample, in order to perform control using different attenuationcoefficients α for use in the fractional transmit power control in acell between the base station 101 and the terminal 102 and between theRRH 103 and the terminal 102, the first uplink power control relatedparameter configuration is associated with transmit power control forthe base station 101, and the second uplink power control relatedparameter configuration is associated with transmit power control forthe RRH 103. Accordingly, the coefficients α included in the respectiveconfigurations can be configured as appropriate values a. That is,fractional transmit power control between the base station 101 and theterminal 102 can be performed in a different way from that between theRRH 103 and the terminal 102. Similarly, P_(O_NOMINAL_PUSCH,c) andP_(O_UE_PUSCH,c) can be set to different values in the first uplinkpower control related parameter configuration and second uplink powercontrol related parameter configuration, making the nominal power of thePUSCH between the base station 101 and the terminal 102 different fromthat between the RRH 103 and the terminal 102. The same applies to theother parameters.

Now referring to FIG. 1, the terminal 102 may be controlled to compute apath loss and an uplink transmit power using the first uplink powercontrol related parameter configuration for the uplink 106, and totransmit an uplink signal at the computed transmit power. The terminal102 may also be controlled to compute a path loss and an uplink transmitpower using the second uplink power control related parameterconfiguration for the uplink 108, and to transmit an uplink signal atthe computed transmit power.

Fourth Embodiment

Next, a fourth embodiment will be described. The description of thefourth embodiment will be directed to a method for the base station 101to configure, in the terminal 102, parameters necessary for connectionprocessing with the base station 101 or the RRH 103.

If an uplink signal is transmitted at the uplink transmit power for thebase station (macro base station) 101 and an uplink signal istransmitted at the uplink transmit power for the RRH 103 on the samecarrier component at the same timing (uplink subframe), problems occurssuch as intersymbol interference, interference caused by out-of-bandradiation, and increase in required dynamic range.

The base station 101 controls the terminal 102 to separate thetransmission of an uplink signal to the base station 101 and thetransmission of an uplink signal to the RRH 103 in the time domain.Specifically, the base station 101 configures the transmission timing ofuplink signals (PUSCH, PUCCH (CQI, PMI, SR, RI, ACK/NACK), UL DMRS, SRS,PRACH) so that the timing at which the terminal 102 transmits an uplinksignal to the base station 101 and the timing at which the terminal 102transmits an uplink signal to the RRH 103 are different. That is, thebase station 101 configures the respective uplink signals so that thetransmission to the base station 101 does not overlap the transmissionto the RRH 103. A variety of uplink physical channels include at leastone (or one type of) uplink physical channel (uplink signal) among theuplink signals (PUSCH, PUCCH (CQI, PMI, SR, RI, ACK/NACK), UL DMRS, SRS,PRACH) described above.

The base station 101 may configure a subset for the transmission timing(uplink subframes) of an uplink signal directed to the base station 101and a subset for the transmission timing (uplink subframes) of an uplinksignal directed to the RRH 103, and may schedule each terminal inaccordance with the subsets.

Furthermore, the base station 101 appropriately configures uplink powercontrol related parameter configurations for the base station 101 andthe RRH 103 so that the transmit power set for an uplink signal to betransmitted to the base station 101 and the transmit power set for anuplink signal to be transmitted to the RRH 103 are appropriate. That is,the base station 101 can perform appropriate uplink transmit powercontrol for the terminal 102.

First, a description will be given of the control of the base station101 in the time domain. The uplink subframe subset for the base station101 is represented by a first uplink subset, and the uplink subframesubset for the RRH 103 is represented by a second uplink subset. In thiscase, the base station 101 configures the values of a variety ofparameters so that each uplink signal is included in the first subset orthe second subset in accordance with whether the terminal 102 accessesthe base station 101 or the RRH 103.

The configuration of the transmission subframes and transmission periodsof the respective uplink signals will now be described. The transmissionsubframe and transmission period of the CQI (Channel Quality Indicator)and PMI (Precoding Matrix Indicator) are configured using a CQI-PMIconfiguration index (cqi-pmi-ConfigIndex). The transmission subframe andtransmission period of the RI (Rank Indicator) are configured using anRI configuration index. For the SRS (Sounding Reference Signal), thecell-specific SRS transmission subframe (transmission subframe andtransmission period) is configured using a cell-specific SRS subframeconfiguration (srs-SubframeConfig), and the UE-specific SRS transmissionsubframe, which is a subset of cell-specific SRS transmission subframes,is configured using a UE-specific SRS configuration index(srs-ConfigIndex). The transmission subframe of the PRACH is configuredusing a PRACH configuration index (prach-ConfigIndex). The transmissiontiming of the SR (Scheduling Request) is configured using an SRconfiguration (sr-ConfigIndex).

The CQI-PMI configuration index and the RI configuration index areconfigured in a CQI report periodic (CQI-ReportPeriodic) included in aCQI report configuration (CQI-ReportConfig). The CQI reportconfiguration is included in the dedicated physical configuration.

The cell-specific SRS subframe configuration is configured in acell-specific sounding UL configuration (SoundingRS-UL-ConfigCommon),and the UE-specific SRS configuration index is configured in aUE-specific sounding UL configuration (SoundingRS-UL-ConfigDedicated).The cell-specific sounding UL configuration is included in a commonradio resource configuration SIB and a common radio resourceconfiguration. The UE-specific sounding UL configuration is included ina dedicated radio resource configuration.

The PRACH configuration index is configured in PRACH configurationinformation (PRACH-ConfigInfo). The PRACH configuration information isincluded in a PRACH configuration SIB (PRACH-ConfigSIB) and a PRACHconfiguration (PRACH-Config). The PRACH configuration SIB is included inthe common radio resource configuration SIB, and the PRACH configurationis included in the common radio resource configuration.

The SR configuration index is included in a scheduling requestconfiguration (SchedulingRequextConfig). The scheduling requestconfiguration is included in the dedicated physical configuration.

Since the PUSCH, the aperiodic CSI, and the aperiodic SRS aretransmitted in the uplink subframe associated with the downlink subframein which the uplink grant has been detected, the base station 101 canperform control to determine whether to transmit the signals to theterminal 102 in the first uplink subset or the second uplink subset bycontrolling the timing of notification of the uplink grant.

The base station 101 configures the indexes concerning the transmissiontiming of the respective uplink signals so that each of the indexes isincluded in the first uplink subset or the second uplink subset.Accordingly, the base station 101 can perform uplink transmissioncontrol of a terminal so that the uplink signal directed to the basestation 101 and the uplink signal directed to the RRH 103 do notinterfere with each other.

In addition, the resource allocation, transmission timing, and transmitpower control of each uplink signal are also configurable for thesecondary cell. Specifically, the cell/UE-specific SRS configuration isconfigured to be secondary cell-specific. The transmission timing andtransmission resource of the PUSCH are specified in the uplink grant.

As also described in the third embodiment, the one or more parametersrelated to uplink power control are configurable for a secondary cell.

The transmit power control of the PRACH will now be described. Theinitial transmit power of the PRACH is computed based on preambleinitial received target power (preambleInitialReceivedTargetPower). Ifrandom access between a base station and a terminal has failed, a powerramping step (powerRampingStep), which is used to increase the transmitpower by a certain amount for transmission, is configured. If randomaccess on a physical random access channel PRACH (Physical Random AccessChannel) transmitted at increasing power has continuously failed and themaximum transmit power of the terminal 102 or the maximum number oftransmissions of the PRACH is exceeded, the terminal 102 determines thatrandom access has failed, and notifies the higher layer of theoccurrence of a random access problem (RAP). In a case where the higherlayer is notified of a random access problem, it is determined that aradio resource failure (RLF: Radio Link Failure) has occurred.

The common radio resource configuration includes P_MAX indicating themaximum transmit power of the terminal 102. The common radio resourceconfiguration for the secondary cell also includes P_MAX. The basestation 101 can configure the maximum transmit power of the terminal 102so as to be primary cell-specific or secondary cell-specific.

The uplink transmit power of the PUSCH, PUCCH, and SRS are as given inthe third embodiment.

By way of example, the base station 101 configures thePUSCH/PUCCH/SRS/PRACH configuration (index) in the time axis included inthe cell-specific/UE-specific radio resource configuration and dedicatedphysical configuration notified using the system information, so thatthe configuration is first included in the first uplink subframe subset.After the establishment of the RRC connection, the base station 101 andthe RRH 103 perform channel measurement or the like for each terminal102 to determine which (of the base station 101 and the RRH 103) theterminal 102 is closer to. If the base station 101 determines, as aresult of the measurement, that the terminal 102 is closer to the basestation 101 than to the RRH 103, the base station 101 does notparticularly change the configuration. If the base station 101determines, as a result of the measurement, that the terminal 102 iscloser to the RRH 103 than to the base station 101, the base station 101notifies the terminal 102 of reconfiguration information (for example,transmit power control information, transmission timing information)suitable for the connection with the RRH 103. Here, the transmit powercontrol information is a general term of transmit power control for therespective uplink signals. For example, a variety of informationelements and TPC commands included in the uplink power control relatedparameter configurations are included in the transmit power controlinformation. The transmission timing information is a general term ofinformation for configuring the transmission timings of the respectiveuplink signals. For example, the transmission timing informationincludes control information concerning transmission timing (the SRSsubframe configuration, the CQI-PMI configuration index, etc.).

The transmission control of an uplink signal (uplink transmission timingcontrol) for the base station 101 or the RRH 103 will now be described.The base station 101 determines whether the terminal 102 is closer tothe base station 101 or the RRH 103, using the measurement results ofindividual terminals. If the base station 101 determines, in accordancewith the measurement results (measurement reports), that the terminal102 is closer to the base station 101 than to the RRH 103, the basestation 101 configures the transmission timing information on therespective uplink signals so that the transmission timing information isincluded in the first uplink subset, and sets the transmit powerinformation to a value suitable for the base station 101. In this case,the base station 101 may not necessarily notify the terminal 102 ofinformation for reconfiguration. That is, the initial configuration isnot updated. If the base station 101 determines that the terminal 102 iscloser to the RRH 103 than to the base station 101, the base station 101configures the transmission timing information on the respective uplinksignals so that the transmission timing information is included in thesecond uplink subset, and sets the transmit power information to a valuesuitable for the RRH 103. Accordingly, the base station 101 can changethe transmission timing to control the transmission of an uplink signalto the base station 101 and the transmission of an uplink signal to theRRH 103, and can control a terminal so that these signals do notinterfere with each other. Here, a terminal 102 that communicates withthe base station 101 is represented by terminal A and a terminal 102that communicates with the RRH 103 is represented by terminal B. Thebase station 101 can configure a variety of configuration indexesincluding transmission timing so that the transmission timing of theterminal B is not equal to that of the terminal A. For example, theUE-specific SRS subframe configuration may be set to different valuesfor the terminal A and the terminal B.

Furthermore, as described in the third embodiment, the base station 101can associate different measurement targets with the first uplink subsetand the second uplink subset.

More specific description of the procedure described above will now beprovided. The base station 101 and/or the RRH 103 broadcasts broadcastinformation specifying a subframe in the first uplink subset as thePRACH configuration in the time axis. A terminal 102 that has not yetcompleted initial access or a terminal 102 in the RRC idle stateattempts initial access on the basis of the acquired broadcastinformation using a PRACH resource in any subframe in the first uplinksubset. In this case, the transmit power of the PRACH is configured withreference to a CRS transmitted from a base station or from a basestation and an RRH. Accordingly, a comparatively high transmit power isobtained, which allows the PRACH to reach the base station 101.

After the RRC connection establishment or during RRC connectionestablishment through random access procedure, a semi-staticallyallocated PUCCH resource for the periodic CSI or Ack/Nack, asemi-statically allocated SRS resource, and a semi-statically allocatedPUCCH resource for the SR are configured. All of these resources areresources in a subframe in the first uplink subset. The base station 101schedules (allocates) to the terminal 102 a PDSCH that allows Ack/Nackto be transmitted on a PUSCH in a subframe in the first uplink subset oron a PUCCH in a subframe in the first uplink subset. In this case, thetransmit powers of the PUSCH, PUCCH, and SRS are set with reference to aCRS transmitted from the base station 101 or from the base station 101and the RRH 103. Accordingly, a comparatively high transmit power isobtained, which allows the PUSCH, PUCCH, and SRS to reach the basestation 101. In this manner, a terminal 102 that performs uplinktransmission at a comparatively high transmit power (a transmit powerthat is sufficient to compensate for a loss between the base station 101and the terminal 102) uses only subframes in the first uplink subset.

Then, the base station 101 determines (judges) whether the terminal 102is to transmit an uplink signal to the base station 101 or transmit anuplink signal to the RRH 103. In other words, the base station 101determines whether the terminal 102 is to perform the transmission at atransmit power that is sufficient to compensate for a loss between thebase station 101 and the terminal 102 or at a transmit power that issufficient to compensate for a loss between the RRH 103 and the terminal102. This determination is based on, as described above, which of thebase station 101 and the RRH 103 the position of the terminal 102 iscloser to, using the measurement results, or any other determinationcriterion may be used. The determination may be based on, for example,the power of a received signal when the RRH 103 receives a signal suchas the SRS transmitted from the terminal 102 in a subframe in the firstuplink subset. If the base station 101 determines that the terminal 102is to transmit an uplink signal to the base station 101, the basestation 101 continues uplink communication using only subframes in thefirst uplink subset.

If the base station 101 determines that the terminal 102 is to transmitan uplink signal to the RRH 103, parameters related to uplink powercontrol are configured so that uplink transmission is performed in theseresources at a comparatively low transmit power (a transmit power thatis sufficient to compensate for a loss between the RRH 103 and theterminal 102). The configuration for reducing the transmit power may beperformed using the method described above in the foregoing embodiments.Any other method may be used, such as a method for reducing powerstep-by-step through iteration of closed-loop transmit power control ora method for updating the configuration of the CRS power value or thechannel loss compensation coefficient α in the system informationthrough a handover procedure.

If the base station 101 determines that the terminal 102 is to transmitan uplink signal to the RRH 103, the semi-statically allocated PUCCHresource for the periodic CSI or Ack/Nack, the semi-statically allocatedSRS resource, and the semi-statically allocated PUCCH resource for theSR are reconfigured. All these resources are resources in a subframe inthe second uplink subset. In addition, the configuration of the PRACHresource in the system information is updated through a handoverprocedure (mobility control procedure). All the PRACH resources areresources in a subframe in the second uplink subset. The base station101 further schedules (allocates) to the terminal 102 a PDSCH thatallows Ack/Nack to be transmitted on a PUSCH in a subframe in the seconduplink subset or on a PUCCH in a subframe in the second uplink subset.In this manner, a terminal 102 that performs uplink transmission at acomparatively low transmit power (a transmit power that is sufficient tocompensate for a loss between the RRH 103 and the terminal 102) usesonly subframes in the second uplink subset.

As described above, a terminal 102 that performs uplink transmission ata comparatively high transmit power (a transmit power that is sufficientto compensate for a loss between the base station 101 and the terminal102) uses subframes in the first uplink subset, whereas a terminal 102that performs uplink transmission at a comparatively low transmit power(a transmit power that is sufficient to compensate for a loss betweenthe RRH 103 and the terminal 102) uses only subframes in the seconduplink subset. Accordingly, subframes received by the base station 101and subframes received by the RRH 103 can be separated in the time axis.This eliminates the need to simultaneously perform reception processingon signals with a high received power and signals with a low receivedpower, and can suppress interference. Furthermore, the required dynamicrange at the base station 101 or the RRH 103 can be reduced.

Here, a description will be given of the transmission control of anuplink signal (uplink transmission resource control) for the basestation 101 or the RRH 103 in carrier aggregation. It is assumed thatthe base station 101 configures two carrier components (first carriercomponent, second carrier component) for the terminal 102 and that afirst carrier component and a second carrier component are configured asthe primary cell and the secondary cell, respectively. If the basestation 101 determines, based on measurement results, that the terminal102 is closer to the base station than to the RRH (terminal A), the basestation 101 sets the secondary cell to be deactivated. That is, theterminal A performs communication without using the secondary cell butusing only the primary cell. If the base station 101 determines that theterminal 102 is closer to the RRH 103 than to the base station 101(terminal B), the base station 101 sets the secondary cell to beactivated.

That is, the terminal B performs communication with the base station 101and the RRH 103 using not only the primary cell but also the secondarycell. The base station 101 configures, as the secondary cellconfiguration for the terminal B, resource allocation and transmit powercontrol suitable for the transmission to the RRH 103. Specifically, thebase station 101 controls the terminal B to compute a path loss and anuplink transmit power taking into account the transmission of path lossmeasurement for the secondary cell from the RRH. Note that the uplinksignals that the terminal B transmits via the secondary cell are thePUSCH, PUSCH demodulation UL DMRS, and SRS. The PUCCH (CQI, PMI, RI),PUCCH demodulation UL DMRS, and PRACH are transmitted via the primarycell. For example, if the terminal B is permitted by the higher layer tosimultaneously transmit the PUSCH and PUCCH, the terminal B iscontrolled to transmit the PUCCH in the primary cell and to transmit thePUSCH in the secondary cell. In this case, the terminal B is controlledby the base station 101 in such a manner that the transmit power for thebase station 101 is set for the primary cell and the transmit power forthe RRH 103 is set for the secondary cell. If the terminal A ispermitted by the higher layer to simultaneously transmit the PUSCH andPUCCH, the terminal A is controlled by the base station 101 to transmitthe PUSCH and PUCCH via the primary cell. Accordingly, the base station101 can change the transmission resource to control the transmission ofan uplink signal to the base station 101 and the transmission of anuplink signal to the RRH 103, and can control the terminal 102 so thatthese signals do not interfere with each other.

In addition, the base station 101 may reconfigure the first carriercomponent as the secondary cell and the second carrier component as theprimary cell for the terminal B by utilizing a handover. In this case,the terminal B performs processing similar to that for the terminal Adescribed above. Specifically, the terminal B deactivates the secondarycell. That is, the terminal B communicates with the RRH without usingthe secondary cell but using only the primary cell. In this case, theterminal B is controlled to transmit all uplink signals via the primarycell. In this case, furthermore, regarding all the uplink transmitpowers, uplink transmit power control for the RRH 103 is carried out.Specifically, the transmit powers of the PUSCH, PUCCH, PRACH, and SRSare reconfigured to be suitable for the RRH 103. In this case,reconfiguration information is included in the RRC connectionreconfiguration.

In addition, the base station 101 can control a terminal not to performcommunication at a high transmit power via the second carrier componentby providing carrier components or cells with access (transmission)restrictions (ac-Barring Factor) on uplink transmit power.

In addition, as described in the third embodiment, the base station 101can associate different measurement targets with the first carriercomponent and the second carrier component or with the primary cell andthe secondary cell.

The procedure described above will now be described in a differentaspect. The base station 101 and the RRH 103 perform communication usinga combination of carrier components, which is a subset of two downlinkcarrier components (component carriers) and two uplink carriercomponents (component carriers). The base station 101 and/or the RRH 103broadcasts broadcast information on restrictions of initial access(preventing initial access) on the second downlink carrier component. Onthe other hand, the base station 101 and/or the RRH 103 broadcastsbroadcast information enabling initial access on the first downlinkcarrier component (does not broadcast the broadcast information onrestrictions of initial access). A terminal that has not yet completedinitial access or a terminal 102 in the RRC idle state attempts initialaccess on the basis of the acquired broadcast information using a PRACHresource in the first uplink carrier component rather than in the seconduplink carrier component. In this case, the transmit power of the PRACHis configured with reference to a CRS transmitted from the base station101 or from the base station 101 and the RRH 103 in the first downlinkcarrier component. Accordingly, a comparatively high transmit power isobtained, which allows the PRACH to reach the base station 101.

After the RRC connection establishment or during RRC connectionestablishment through random access procedure, a semi-staticallyallocated PUCCH resource for the periodic CSI or Ack/Nack, asemi-statically allocated SRS resource, and a semi-statically allocatedPUCCH resource for the SR are configured. These resources are resourcesin the first uplink carrier component, that is, resources in the primarycell (PCell: a cell including the first downlink carrier component andthe first uplink carrier component). The base station 101 schedules(allocates) a PUSCH in the first uplink carrier component to theterminal 102. The terminal 102 further transmits an Ack/Nack for a PDSCHin the first downlink carrier component using a PUCCH in the firstuplink carrier component. In this case, the transmit powers of thePUSCH, PUCCH, and SRS are set with reference to a CRS transmitted fromthe base station 101 or from the base station 101 and the RRH 103 in thePCell. Accordingly, a comparatively high transmit power is obtained,which allows the PUSCH, PUCCH, and SRS to reach the base station 101.

In a case where carrier aggregation is to be performed, the secondarycell (SCell) is configured as a cell having the second downlink carriercomponent (having no uplink carrier components). In the SCell, thesemi-statically allocated PUCCH resources for the periodic CSI orAck/Nack are resources in the first uplink carrier component, that is,resources in the PCell. The terminal 102 transmits an Ack/Nack for aPDSCH in the second downlink carrier component (SCell) using a PUCCH inthe first uplink carrier component (PCell). In this case, the transmitpowers of the PUSCH, PUCCH, and SRS are set with reference to a CRStransmitted from the base station 101 or from the base station 101 andthe RRH 103 in the PCell. Accordingly, a comparatively high transmitpower is obtained, which allows the PUSCH, PUCCH, and SRS to reach thebase station 101. In this manner, a terminal 102 that performs uplinktransmission at a comparatively high transmit power (a transmit powerthat is sufficient to compensate for a loss between the base station 101and the terminal 102) uses only the first uplink carrier componentregardless of whether carrier aggregation is performed or not.

Then, the base station 101 determines whether the terminal 102 is totransmit an uplink signal to the base station 101 or to transmit anuplink signal to the RRH 103. In other words, the terminal 102determines whether the terminal 102 is to perform the transmission at atransmit power that is sufficient to compensate for a loss between thebase station 101 and the terminal 102 or at a transmit power that issufficient to compensate for a loss between the RRH 103 and the terminal102. This determination can be based on the method described above. Ifthe base station 101 determines that the terminal 102 is to transmit anuplink signal to the base station 101, the base station 101 continuesuplink communication using only the first uplink carrier component, thatis, communication in which a cell including the first downlink carriercomponent and the first uplink carrier component is set as the PCell.

If the base station 101 determines that the terminal 102 is to transmitan uplink signal to the RRH 103, the base station 101 changes the PCellthrough a handover procedure. Specifically, the PCell is changed from aPCell having the first downlink carrier component and the first uplinkcarrier component to a PCell having the second downlink carriercomponent and the second uplink carrier component. In the handoverprocedure, the parameters related to uplink power control are configuredin such a manner that uplink transmission is performed at acomparatively low transmit power (a transmit power that is sufficient tocompensate for a loss between the RRH 103 and the terminal 102) afterthe handover has been completed. Any other method may be used, such as amethod for updating the configuration of the CRS power value, thechannel loss compensation coefficient α, or the initial value of theuplink transmit power in the system information. In addition, systeminformation with no restrictions of initial access is configured.

In a case where the PCell has been changed, the random access procedureon the second uplink carrier component is performed and an RRCconnection is established. After the RRC connection establishment orduring RRC connection establishment through the random access procedure,a semi-statically allocated PUCCH resource for the periodic CSI orAck/Nack, a semi-statically allocated SRS resource, and asemi-statically allocated PUCCH resource for the SR are reconfigured.All of these resources are resources in the second uplink carriercomponent. The base station 101 schedules (allocates) to the terminal102 a PDSCH that allows Ack/Nack to be transmitted on a PUSCH in thesecond uplink carrier component or on a PUCCH in the second uplinkcarrier component. In this case, the parameters related to uplink powercontrol are configured in such a manner that the transmit powers of thePUSCH, PUCCH, and SRS are comparatively low (sufficient to compensatefor a loss between the RRH 103 and the terminal 102).

In a case where carrier aggregation is to be performed, the SCell isconfigured as a cell having the first downlink carrier component (havingno uplink carrier components). In the SCell, the semi-staticallyallocated PUCCH resources for the periodic CSI or Ack/Nack are resourcesin the second uplink carrier component, that is, resources in the PCell.The terminal 102 transmits an Ack/Nack for a PDSCH in the SCell using aPUCCH in the second uplink carrier component. In this case, theparameters related to uplink power control are set in such a manner thatthe transmit power of the PUCCH is comparatively low (sufficient tocompensate for a loss between the RRH 103 and the terminal 102). In thismanner, a terminal 102 that performs uplink transmission at acomparatively low transmit power (a transmit power that is sufficient tocompensate for a loss between the RRH 103 and the terminal 102) usesonly the second uplink carrier component regardless of whether carrieraggregation is performed or not.

As described above, a terminal 102 that performs uplink transmission ata comparatively high transmit power (a transmit power that is sufficientto compensate for a loss between the base station 101 and the terminal102) uses the first uplink carrier component, whereas a terminal 102that performs uplink transmission with a comparatively low transmitpower (a transmit power that is sufficient to compensate for a lossbetween the RRH 103 and the terminal 102) uses only the second uplinkcarrier component. Accordingly, subframes received by the base station101 and subframes received by the RRH 103 can be separated in thefrequency axis. This eliminates the need to simultaneously performreception processing on signals with a high received power and signalswith a low received power, and can suppress interference. Furthermore,the required dynamic range at the base station 101 or the RRH 103 can bereduced.

Here, a description will be given of the transmission control of anuplink signal (uplink signal transmit power control) for the basestation 101 or the RRH 103 in a control channel (PDCCH) region includingan uplink grant. If the base station 101 determines, based onmeasurement results, that a certain terminal (terminal A) is close tothe base station 101, the base station 101 performs dynamic uplinksignal transmission control for the terminal A only in the first controlchannel (PDCCH) region. If the base station 101 determines, based onmeasurement results, that a certain terminal (terminal B) is close tothe RRH 103, the base station 101 performs dynamic uplink signaltransmission control for the terminal B only in the second controlchannel (X-PDCCH) region. More specifically, in order to cause theterminal 102 to transmit an uplink signal to the base station 101, thebase station 101 notifies the terminal 102 of an uplink grant that isincluded in the first control channel region. In order to cause theterminal 102 to transmit an uplink signal to the RRH 103, the basestation 101 notifies the terminal 102 of an uplink grant that isincluded in the second control channel region.

In addition, the base station 101 can utilize a TPC command, which is acorrection value for uplink signal transmit power control included inthe uplink grant, to perform uplink signal transmit power control forthe base station 101 or the RRH 103. The base station 101 configures aTPC command value included in the uplink grant so as to be suitable forthe base station 101 or the RRH 103 in accordance with the controlchannel region in which the base station 101 notifies the terminal 102of the uplink grant. More specifically, in order to increase the uplinktransmit power for the base station 101, the base station 101 sets thepower correction value of the TPC command in the first control channelregion to be high. In order to decrease the uplink transmit power forthe RRH 103, the base station 101 sets the power correction value of theTPC command in the second control channel region to be low. The basestation 101 performs uplink signal transmission and uplink transmitpower control for the terminal A using the first control channel region,and performs uplink signal transmission and uplink transmit powercontrol for the terminal B using the second control channel.

In addition, as described in the third embodiment, the base station 101can associate different measurement targets with the first controlchannel region and the second control channel region.

In the fourth embodiment, the base station 101 configures transmissiontiming information on the physical random access channel, which isincluded in system information, in a subframe in the first subframesubset, and configures transmission timing information on a variety ofuplink physical channels in a subframe in the first subframe subset.Furthermore, the base station 101 reconfigures the radio resourcecontrol information for some terminals 102. In this case, transmissiontiming information on the physical random access channel, which isincluded in a radio resource control signal, is configured in a subframein the second subframe subset different from the first subframe subset,and the transmission timing information on a variety of uplink physicalchannels is configured in a subframe in the second subframe subset.

In addition, the base station 101 configures transmit power controlinformation on a variety of uplink signals as first transmit powercontrol information in association with the first subframe subset, andreconfigures the radio resource control information for some terminals102. In this case, the transmit power control information on a varietyof uplink signals is configured as second transmit power controlinformation in association with the second subframe subset.

In addition, the base station 101 configures first transmit powercontrol information for a terminal 102 that transmits an uplink signalin the first subframe subset, and configures second transmit powercontrol information for a terminal 102 that transmits an uplink signalin the second subframe subset.

In the fourth embodiment, furthermore, the base station 101 transmits asignal via the first downlink carrier component and the second downlinkcarrier component. The base station 101 configures first transmit powercontrol information as primary cell-specific transmit power controlinformation for a terminal 102 for which the first downlink carriercomponent is configured as the primary cell, and configures secondtransmit power control information as primary cell-specific transmitpower control information for a terminal 102 for which the seconddownlink carrier component is configured as the primary cell.

In addition, the base station 101 receives a signal via the first uplinkcarrier component and the second uplink carrier component. The basestation 101 configures first transmit power control information for aterminal 102 that performs communication via the first uplink carriercomponent, and configures second transmit power control information fora terminal 102 that performs communication via the second uplink carriercomponent.

The base station 101 controls a terminal 102 that accesses the basestation 101 and a terminal 102 that accesses the RRH 103 to transmit anuplink signal in accordance with time, frequency, and a control channelregion including an uplink grant. Accordingly, the base station 101 canperform appropriate transmission timing control, appropriate radioresource control, and appropriate uplink transmit power control.

The base station 101 configures a variety of parameters such that allthe transmit power control information and transmission timinginformation concerning uplink signals, which are included in systeminformation, are appropriately configured for the base station 101.After the establishment of initial connection (RRC connectionestablishment), while the base station 101 and the terminal 102communicate with each other, the base station 101 determines, based onthe results of channel measurement and so forth, whether the terminal102 is closer to the base station 101 or to the RRH 103. If the basestation 101 determines that the terminal 102 is closer to the basestation, the base station 101 does not particularly notify the terminal102 of configuration information, or configures transmit power controlinformation, transmission timing control information, and transmissionresource control information which are more suitable for communicationwith the base station 101 and notifies the terminal 102 of theconfigured information through RRC connection reconfiguration. If thebase station 101 determines that the terminal 102 is closer to the RRH103, the base station 101 configures transmit power control information,transmission timing control information, and transmission resourcecontrol information which are suitable for communication with the RRH103, and notifies the terminal 102 of the configured information throughRRC connection reconfiguration.

The foregoing embodiments have been described using, for example, butnot limited to, a resource element or a resource block as the unit ofmapping an information data signal, a control information signal, aPDSCH, a PDCCH, and reference signals and using a subframe or a radioframe as the unit of transmission in the time domain. Similar advantagescan be achieved with the use of any desired frequency and time domainsand the time unit instead of them. The foregoing embodiments have beendescribed using, by way of example, but not limited to, the case wheredemodulation is carried out using RSs subjected to precoding processingand using ports equivalent to the layers of MIMO as the portscorresponding to the RSs subjected to precoding processing.Additionally, similar advantages can also be achieved by applying thepresent invention to ports corresponding to different reference signals.For example, in place of precoded RSs, unprecoded (nonprecoded) RSs maybe used, and ports equivalent to the output edges after the precodingprocessing has been performed or ports equivalent to physical antennas(or a combination of physical antennas) may be used as ports.

The foregoing embodiments have been described in terms ofdownlink/uplink coordinated communication between the base station 101,the terminal 102, and the RRH 103. The present invention can also beapplied to coordinated communication between two or more base stations101 and the terminal 102, coordinated communication between two or morebase stations 101, the RRH 103, and the terminal 102, coordinatedcommunication between two or more base stations 101 or the RRH 103 andthe terminal 102, coordinated communication between two or more basestations 101, two or more RRHs 103, and the terminal 102, andcoordinated communication between two or more transmissionpoints/reception points. Furthermore, the foregoing embodiments havebeen described in terms of uplink transmit power control suitable forcommunication between the terminal 102 and one of the base station 101and the RRH 103 to which the terminal 102 is closer, based on thecomputational results of path loss. However, similar processing can beperformed for uplink transmit power control suitable for communicationbetween the terminal 102 and one of a base station and the RRH 103 fromwhich the terminal 102 is more distant, based on the computationalresults of path loss.

A program operating in the base station 101 and the terminal 102according to the present invention is a program (a program for causing acomputer to function) to control a CPU and so forth so as to implementthe functions of the foregoing embodiments according to the presentinvention. Such information as handled by devices is temporarilyaccumulated in a RAM while processed, and is then stored in various ROMsand HDDs. The information is read by the CPU, if necessary, formodification/writing. A recording medium having the program storedtherein may be any of semiconductor media (for example, a ROM, anon-volatile memory card, etc.), optical recording media (for example, aDVD, an MO, an MD, a CD, a BD, etc.), magnetic recording media (forexample, a magnetic tape, a flexible disk, etc.), and so forth.Furthermore, in addition to the implementation of the functions of theembodiments described above by executing the loaded program, thefunctions of the present invention may be implemented by processing theprogram in cooperation with an operating system, any other applicationprogram, or the like in accordance with instructions of the program.

To distribute the program to the market, the program may be stored in atransportable recording medium for distribution, or may be transferredto a server computer connected via a network such as the Internet. Inthis case, a storage device in the server computer also falls within thescope of the present invention. In addition, part or the entirety of thebase station 101 and the terminal 102 in the embodiments described abovemay be implemented as an LSI, which is typically an integrated circuit.The respective functional blocks of the base station 101 and theterminal 102 may be individually built into chips or some or all of themmay be integrated and built into a chip. The method for forming anintegrated circuit is not limited to LSI, and may be implemented by adedicated circuit or a general-purpose processor. In the case of theadvent of integrated circuit technology replacing LSI due to theadvancement of semiconductor technology, it is also possible to use anintegrated circuit bead on this technology.

While embodiments of this invention have been described in detail withreference to the drawings, a specific configuration is not limited tothat in these embodiments, and design changes and the like withoutdeparting from the essence of this invention also fall within theinvention. In addition, a variety of changes can be made to the presentinvention within the scope defined by the claims, and embodiments thatare achievable by appropriately combining respective technical meansdisclosed in different embodiments are also embraced within thetechnical scope of the present invention. Furthermore, a configurationin which elements described in the foregoing embodiments and capable ofachieving similar advantages are interchanged is also embraced withinthe technical scope of the present invention. The present invention issuitable for use in a radio base station device, a radio terminaldevice, a radio communication system, and a radio communication method.

REFERENCE SIGNS LIST

-   -   101, 3401 base station    -   102, 3402, 3403, 3504, 3604 terminal    -   103, 3502, 3602 RRH    -   104, 3503, 3603 line    -   105, 107, 3404, 3405, 3505, 3506 downlink    -   106, 108, 3605, 3606 uplink    -   501 higher layer processing unit    -   503 control unit    -   505 receiving unit    -   507 transmitting unit    -   509 channel measurement unit    -   511 transmit/receive antenna    -   5011 radio resource control unit    -   5013 SRS configuration unit    -   5015 transmit power configuration unit    -   5051 decoding unit    -   5053 demodulation unit    -   5055 demultiplexing unit    -   5057 radio receiving unit    -   5071 coding unit    -   5073 modulation unit    -   5075 multiplexing unit    -   5077 radio transmitting unit    -   5079 downlink reference signal generation unit    -   601 higher layer processing unit    -   603 control unit    -   605 receiving unit    -   607 transmitting unit    -   609 channel measurement unit    -   611 transmit/receive antenna    -   6011 radio resource control unit    -   6013 SRS control unit    -   6015 transmit power control unit    -   6051 decoding unit    -   6053 demodulation unit    -   6055 demultiplexing unit    -   6057 radio receiving unit    -   6071 coding unit    -   6073 modulation unit    -   6075 multiplexing unit    -   6077 radio transmitting unit    -   6079 uplink reference signal generation unit    -   3501, 3601 macro base station

1. A terminal device comprising: higher layer processing circuitryconfigured to receive a first reference signal configuration and areport configuration via a radio resource control signal, the firstreference signal configuration comprising one or more combinations offirst channel state information reference signal (CSI-RS) index and aCSI-RS measurement configuration, and the report configurationcomprising one or more second CSI-RS indices; measurement circuitryconfigured to measure reference signal received powers (RSRPs) of one ormore first CSI-RSs respectively identified by one or more first CSI-RSindices; and transmitting circuitry configured to transmit a measurementreport based on the report configuration, wherein the measurement reportincludes the one or more second CSI-RS indices and the respective RSRPsof the one or more first CSI-RSs identified by the one or more secondCSI-RS indices.